AU2014208288A1 - Improvements in and relating to rock treatment process - Google Patents

Abstract

Abstract This invention relates to improvements in and relating to a method for a rock treatment process for reducing the cadmium content of phosphate rock, including a substantially improved apparatus to facilitate reduction of the cadmium content whilet retaining reactivity; and wherein 5 the phosphate rock is used for the subsequent production of soil treatment fertiliser products in granular form. The invention relates to calcining apparatus for use with a rock treatment process. The calcining apparatus includes a chamber for receiving a source of rock to be treated. The calcining apparatus also includes means to introduce the rock material into the chamber. The 10 chamber is adapted to receive a heated gaseous flow; heated via means to achieve a predetermined temperature required to treat the rock. The calcining apparatus including centrifugal means and collection means. The calcining apparatus characterised by using rock material pre-ground to particles of less than 500 micron. -c- ------- 1: qV Ila1

Description

IMPROVEMENTS IN AND RELATING TO ROCK TREATMENT PROCESS Technical Field This invention relates to improvements in and relating to methods for a rock treatment process for reducing the cadmium content of phosphate rock. 5 Particularly, in relation to the rock treatment process, this invention is further directed to providing a substantially improved apparatus to facilitate the method for reducing the cadmium content of phosphate rock. The apparatus and method enable the improved production of a treated phosphate rock product having reduced cadmium content yet with retained reactivity. 10 In addition, the present invention is directed to the use of the phosphate rock, with reduced cadmium content, for the subsequent production of soil treatment fertiliser products. In addition, the invention is further directed to the use of the phosphate product in the manufacture of a soil treatment fertiliser product manufactured in granular form for improved optimal delivery of the phosphate into and on to the soil as well as for improved application, 15 storage and transportation of the fertiliser product. It is envisaged the invention will be applicable to providing an improved phosphate product for use in a range of industries, for example agricultural, horticultural, forestry, commercial, industrial or domestic situations. The invention may also have applications outside the field of processing phosphate rock for soil 20 treatment compositions in granular form. Accordingly, the methods and apparata may be applied to use in other situations where improved calcining and products derived therefrom, are required. Background Art Phosphate rocks are used directly in the production of and as fertilisers and are used indirectly 25 in the production of phosphoric acid and superphosphate fertilisers. Phosphate rock, irrespective of where it is sourced, includes varying levels of Cadmium. Some sources are lower than others, but such sources tend to be available at higher prices. 1 Irrespective of the price or source of the Phosphate Rock, its use in fertilsers and the cadmium levels in the phosphate rock used to produce such fertilisers, has resulted in a notable increase of cadmium in soils. In addition, the cadmium levels have risen dramatically with the respective phosphate-fertilised soils resulting in higher cadmium levels subsequently being 5 found in the food products farmed, grown and supplied from these areas. The introduction of cadmium via phosphate fertilisers presents a significant and well established risk to human and animal health and threatens the sustainability, diversity and food chains of the relevant ecosystems exposed to increasing levels of Cadmium through application of cadmium containing phosphate fertilisers applied to soils and crops. 10 In New Zealand, this problem is reaching crisis point. Soil cadmium levels in regions that have been heavily fertilised with phosphate fertilisers are becoming too high to safely consume certain foods produced there. Given the half life and retention of cadmium in the various ecosystems, there is an urgent need for intervention to lower cadmium levels now, before the point of no return is reached. The 15 most obvious solution is to reduce the levels of cadmium in phosphate fertilisers to reduce the impact of phosphate fertilisers on soil cadmium levels. European countries are in the process of imposing stricter cadmium limits on fertilisers used and those regulations are likely to be imposed on and in New Zealand and other countries in the future. Exports from New Zealand may be detrimentally affected should stricter controls be 20 imposed on cadmium levels in New Zealand's crop and animal food exports. Concerns about fertiliser cadmium levels are not new and as such various methods have been proposed and even developed to attempt to remove cadmium from and/or reduce cadmium levels in phosphate rock and phosphoric acid. With one exception (see below) none of these cadmium removal methods have been commercially implemented, because they were 25 considered to be commercially unviable for a variety of reasons. The exception mentioned above is the calcination (or heating) of phosphate rock. High-temperature calcination is the main physical process that has been used to remove cadmium from phosphate rock, on a commercial scale. However, the manufacturing plant to undertake this process requires high energy input and as a result, one full-scale plant brought into operation was eventually 2 discontinued due to the costs associated with the supply of energy to meet the high energy requirements of the process. It is to be noted that there are various calcination methods mentioned in the literature. These include the use of fluid beds and flash calcining. The present invention considers previous 5 systems, but introduces an improved method of manufacture using flash calcination to remove cadmium from phosphate rocks. Calcination involves heating of the phosphate rock to a temperature higher than the boiling point of cadmium in order to effect the removal of the cadmium. Flash calcining uses flames and short residence times to effect rapid product calcining. The main advantage of using rapid 10 heating/short residence time flash-calcining techniques is that the recombination of the volatised cadmium with the phosphate rock is able to be substantially minimised. Other kiln calcining techniques are not conducive to immediately and continuously remove the volatised cadmium. Calcination using conventional kilns such as rotary calciners can cause the collapse of the phosphate particle surface area and loss of reactivity - as the result of a process 15 called sintering. Therefore, when removing cadmium it is important to disrupt the crystal structure of the apatite as little as possible to ensure the reactivity is not reduced. This is achieved primarily through controlling the temperature and atmosphere (preferably a neutral or non-oxidising atmosphere). Calcination is most efficient in a reducing atmosphere. 20 Flash calcining enables surface area structures of the phosphate rock and particles thereof to be preserved resulting in a more reactive product - a key feature of phosphate fertilisers. As a result of a combination of regulatory pressures and energy efficient technological developments, the implementation and development of methods to remove cadmium from phosphate rock has never been more needed, or more potentially commercially viable. 25 For example, in previous descriptions (NZ594880) the removal of cadmium from the softer and typically finer portions of phosphate rock was discussed. It was noted that by removing the cadmium preferentially from the smallest size material, total cadmium levels could be reduced by as much as 17%. 3 While the present invention has a number of potentially realisable applications, it is in relation to problems associated with the existing use of Phosphate rock in soil treatment and fertilising systems having unacceptable levels of cadmium remaining; and also, the problems associated with the Phosphate rock used and the methods of manufacturing the phosphate products derived 5 therefrom, that the present invention was developed. More specifically, it was with regard to the need to provide a method of preparing soil treatment compositions using phosphate rock - preferably in granular form - and produced so the treatment compositions have substantially reduced levels of cadmium - that the present invention was developed. 10 It was also developed with safety and health issues typically associated with the use of high cadmium content phosphate fertilisers, along with addressing environmental concerns relevant to the application of such fertilisers that the present invention was developed. Finally, it was having regard to the need to develop an improved method to remove cadmium from phosphate rock in order to produce fertilisers cost effectively and to a substantially 15 improved standard where the cadmium levels are substantially reduced. It would be useful therefore, to have an improved process for manufacturing phosphate fertiliser products from phosphate rock, for application on to and/or in to soils that: 1. Was produced using phosphate rock that was subjected to a treatment/manufacturing process to substantially reduced the cadmium content therein; and yet 20 2. Produced a treated phosphate rock product that retained beneficial reactivity; and 3. Could enable granular fertiliser products to be produced using said treated phosphate rock; and 4. Was able to be undertaken commercially at a sustainable and economic level; and 5. Considered and improved on safety and health issues of existing systems; and 25 6. Was effective at mobilising nutrients and/or soil enhancing components so that good plant growth could be achieved with lower nutrient densities; and yet, 7. Minimised the continued build-up of potentially toxic products - such as cadmium - in soils, plants and animals; and so also potentially, 8. Effected reduced environmental impact through run-off, air dispersal and so had regard to 30 environmental concerns existing with current phosphate fertiliser applications; and 4 9. Contributed where appropriate to improving the soil structure; and 10. Provided a more cost effective alternative to present systems employed, including costs of handling, transportation and application costs, and 11. Provided a consistent product, so that accurate application of nutrients to match soil type 5 and plant production was possible; and 12. Would be an easier process to undertake; and that could 13. Achieve consistent results. It would therefore be advantageous to have an invention that offered at least some, if not all, of the potential advantages of the above proposed means for the treatment of phosphate rock and 10 the production of such soil treatments. It is therefore an object of the present invention to consider the above problems and provide at least one solution which addresses a plurality of these problems. It is another object of the present invention to at least provide the public with a useful choice or alternative system. 15 Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. It should be appreciated that variations to described embodiments are possible and would fall within the scope of the present invention. It is a therefore, a further object of the present invention that whilst the invention is described with reference to cadmium removal from 20 phosphate rock, that the resultant product is adapted to be used to produce fertilisers relevant for use in a number of applications and that other soil treatment components may be added to produce granular fertilisers relevant for use in a number of applications; and in addition, where the soil treatment components (including the phosphate rock) are preferably processed into granular form for one or more of improved application, storage, handling and transportation. 25 Disclosure of Invention The present invention is directed to improved calcining methods and apparata used therewith. Particularly, the present invention is directed to improved rock treatment processes. Accordingly, in one embodiment, the invention is specifically directed for use with reactive phosphate rock (RPR) and phosphate rock (PR). Further a specific embodiment is directed to a 5 rock treatment process for reducing the cadmium content of RPR and phosphate rock that is able to subsequently produce a treated phosphate rock product with reduced cadmium levels and yet retained reactivity. It is well known that phosphate rock and reactive phosphate rock have relatively high levels of 5 cadmium which is a toxic metal. The present invention is provided to offer a practical, economic and environmentally focused solution to removing the cadmium from such rock. In addition, the present invention is directed to the use of the phosphate rock, with reduced cadmium content, in the production of soil treatment fertiliser products. The present invention is anticipated to provide consumers with a fertiliser product that is a substantial improvement 10 over existing reactive phosphate rock and phosphate rock fertiliser products that have not had the cadmium removed at all, or to any substantially acceptable extent. In addition, the invention is further directed to the use of the phosphate product in the manufacture of a soil treatment fertiliser product produced in granular form for improved optimal delivery of the phosphate into the soil as well as for improved application, storage and 15 transportation of the fertiliser product. The method of manufacture of the present invention presents several substantially significant novel aspects when compared with other existing cadmium removal methods. The calcining apparatus circuit of the present application is considered to also be substantially unique in the removal of cadmium from phosphate rock (PR). 20 The method applied is an improved flash calcining method. This method of manufacture specifically relates to a calcining method directed to remove cadmium from phosphate rock (PR) and reactive phosphate rock (RPR). Hereafter this class of minerals may be generally referred to simply as phosphate rock (PR), although references to Reactive Phosphate Rock and Phosphate Rock will be relevant in specific instances. 25 While one embodiment of the present invention relates to the improved flash calcining method applied to effecting the reduction of the cadmium content of phosphate rock, it should be appreciated that the present invention may be used for, or adapted for use for the treatment of other rocks. It should also be appreciated that the present invention relates to the improved flash calcining method applied to effecting the reduction of the cadmium content of phosphate 6 rock, where the phosphate rock used is obtained from a range of sources/countries with varying concentrations of cadmium levels associated therewith. Reactive phosphate rock and phosphate rock added to soils with over 6ppm cadmium have been shown to accumulate cadmium in soil over time. The cadmium then bio-accumulates in 5 plants and animals, both on land and potentially in waterways. If cadmium continues to be added to soils (and to waterways through runoff), at current rates, these plants and animals will become unsafe for human consumption. One potentially realisable advantage of the present invention is therefore, that in reducing the cadmium content of phosphate rock, there are substantial benefits in minimising the quantity and rate of accumulation of cadmium in 10 ecosystems, including minimising the concentration of cadmium in soils, waterways, crops and animals from phosphate fertilisers produced from such treated phosphate rock and applied to soils. Over time, using phosphate fertilisers with substantially reduced and/or minimal/eliminated cadmium content, will enable ecosystems and food chains to recover from the cadmium loads currently existing. 15 In addition, a further potentially realisable advantage of the present invention is the ability to use otherwise poor quality sources of phosphate rock. Poor quality phosphate rock - often being high cadmium content phosphate rock - is more cheaply sourced, but less desirable. By reducing the cadmium content to levels not previously possible, the use of such phosphate rock becomes viable and commercially advantageous. 20 In addition, another potentially realisable advantage of the present invention is that the method enables the phosphate rock to be treated and cadmium removed, without compromising the reactivity of the phosphate rock for use in fertiliser products. This particular type of calcining apparatus and methodology has, to the knowledge of the applicant, never previously been used to remove cadmium from RPR or Phosphate rock in the 25 manner as described herein. While it is preferable to reduce the cadmium content to an absolute minimum, often practical requirements may dictate that certain levels of cadmium are deemed acceptable in phosphate rock and in the treated phosphate rock product resulting from implementation of the present invention. This may be dictated by cost considerations, availability of the source phosphate 30 rock and the level of cadmium it contains, and so forth. 7 Therefore, in the practical application of the present invention, a first stage is preferably to decide the amount of cadmium the final phosphate rock product is to contain. Accordingly, in such instances, before the Reactive Phosphate Rock (RPR) is fed into the calcination plant, the source feed material - being the RPR to be used - is split so as to create 5 two reservoirs of material. One reservoir will be treated and will, as such, become the calcined material, the other will not. The quantity of RPR in each of the two reservoirs is determined so that the minimum amount of RPR held in the reservoir to be the calcined material, is fed to the calcination plant as would be necessary to attain a final calcined /uncalcined product effected from the subsequently recombining of the two reservoirs (treated and untreated), whereby the 10 combined product is deemed to have a preferred/ acceptable cadmium component. After being calcined, the stream of calcined RPR is re-combined with the un-calcined RPR. The heat of the calcined RPR as it leaves the calcination chamber is maintained to a level that, when the calcined phosphate rock is mixed with the un-calcined phosphate rock, the heat is sufficient to be able to granulate the total combined phosphate rock without the addition of 15 further heat and/or time, as would normally be required to dry out the formed granules. In accordance with the present invention there is also another additional stage undertaken prior to the calcination process being commenced. This involves finely grinding the phosphate rock to predetermined and preferred particle size(s). Fine grinding of the phosphate rock is preferable at this stage as the phosphate rock to undergo the calcining process is then made up 20 of phosphate rock particles particularly suited to improved removal of cadmium therefrom; and, in addition, finely ground phosphate rock particles (whether the calcined phosphate rock, or the uncalcined phosphate rock) in the finished phosphate product are preferred for subsequent use as an applied fertiliser product in terms of enhanced availability to plants when applied on to or into soils. 25 For example, a Reactive Phosphate Rock product which is comprised of particles finer than conventional RPR, will react more quickly in colder climates, making the finely ground and treated RPR of the present invention a viable product in such regions. Therefore, prior to initiating the cadmium removal process, preferably up to at least 95% of the phosphate rock is ground to particles sized between minus 500 micron to minus 20 microns. 8 A number of potentially realisable benefits arise from using finer phosphate rock particles. For example, in the calcination/cadmium removal process, a lower temperature is able to be used in the calcination process; and also, the smaller particles minimise the retention time of the material as it passes through the calcination apparatus - thus preserving the apatite crystalline 5 structure of the phosphate rock. With fine phosphate rock particles, the cadmium associated therewith is also more exposed to heated air introduced to the particles (as part of the method to be subsequently described). In addition, fine grinding results in particles having a larger surface area. This in turn results in greater cadmium stripping by process air compared with larger particles. 10 As mentioned in the applicant's New Zealand Patent 594880, particles in air travel slower than the air itself. This results in a stripping type action (clothes on the clothesline analogy) which will assist in removing cadmium at lower temperatures - as will be subsequently described with reference to the method of the present invention. This has regard to the fact that in order to effect calcination according to one embodiment of 15 the present invention, the method involves a slow, yet controlled, long-residence-time, heat application to the RPR. Also, reactivity of phosphate rock can be lost during calcination processes. However, grinding the phosphate rock to extra fine particles assists in overcoming this. Multistage cyclone systems can be used to fine particles down to 0.5 microns. However, prior 20 to calcining, some ultrafine phosphate rock particles may be removed, from the source material to be calcined. This is because very fine particles may be difficult to process. According to one aspect of the present invention, there is provided calcining apparatus for use with a rock treatment process, said calcining apparatus including: a chamber for receiving a source of rock to be treated, and said calcining apparatus also including means to introduce the 25 rock material into the chamber; said chamber being adapted to receive a flow of at least one of water, air and at least one other gas; said flow being associated with ignition means, said ignition means effecting a primary heat source applied to said flow; said chamber including or being associated with secondary heating means; and said calcining apparatus including centrifugal means and collection means. 9 According to another aspect of the present invention, there is provided calcining apparatus for use with a rock treatment process, substantially as described above wherein the chamber is located substantially adjacent to the centrifugal means, and whilst in communication therewith, is distanced therefrom. 5 In a preferred embodiment of the present invention, the finely ground RPR is introduced into the chamber. As regards the means used to introduce the rock material into the chamber and the process involved, the finely ground phosphate rock to be calcined is located in a hopper. In one preferred embodiment of the present invention, the finely ground phosphate rock is gradually 10 introduced into the chamber from the hopper via a variable speed driven auger or other delivery means adapted for use with the invention. A motor with a variable speed drive, or equivalent means, is used so that the speed of entry of the finely ground phosphate rock particles into the chamber is able to be adjusted to optimise the process. Flow measuring apparatus may also be included to enable the amount released from the hopper to be delivered to the chamber to be 15 measured at a rate per minute. Depending on the flow rate, the speed of the auger/motor drive is able to be slowed down or sped up to ensure the preferred predetermined rate of delivery is achieved. According to one embodiment of the present invention, the chamber is substantially vertical. The chamber is preferably also substantially elongate. 20 In addition, in preferred embodiments, the first chamber is substantially tubular (cylindrical). In preferred embodiments, the chamber includes a lining located immediately adjacent the internal face of the inner wall of the chamber. The lining is preferably of a material that is adapted to withstand intense heat. While a ceramic lining is preferred, other suitable materials may be employed with or adapted for use in the chamber, as required to effect the desired 25 outcome. Accordingly an example of another potentially suitable lining may be concrete. The lining is included to offer a refractory protective layer between the internal cavity of chamber and the wall of the chamber. During the calcining process, the temperature in the chamber is capable of reaching at least 1000 degree Celsius, or more. The steel cylinder forming the chamber is typically made of metal. In embodiments where the chamber is made 10 of steel, the heat at 1000 degrees Celsius will begin to melt the steel of the cylinder. The lining preserves the integrity of the chamber and retains the heat generated during the calcining process, within the chamber. Due to the temperatures generated within the calcining apparatus, the external surface of the 5 chamber may also be lagged. The lagging is a protective coating, but also contributes to maintaining the temperatures achieved within the chamber. Further, the chamber is preferably configured to include sections of increasing and decreasing internal diameters. The sections of increasing and decreasing internal diameters of the chamber are configured to affect the rate of flow of introduced air flowing through the chamber. The 10 wider and narrower internal sections result in expansion and restriction of the airflows, respectively. The air flows are preferably tangential, upward flowing rising air and, if desired, can be a steam-heated airflow. The overall effect is preferably to slow down the rate of any air flows (heated or otherwise) 15 introduced into the chamber as part of the treatment process. As such the first vertical chamber operates to substantially slow down the air flows, increasing the residency time of the air and associated finely ground rock particles - within the vertical chamber. The use of slow airflows is an advantage because RPR is highly abrasive. 20 The airflow is introduced into the bottom of the chamber via a blower or other air input means. The rate of air introduced is adjustable, by adjusting the speed of the blower, depending on the amount of air required for the process. A low air volume is preferably used initially. This means that less air needs to be handled at the subsequent cadmium removal stage of the process. 25 The air is preferably mixed also with a flammable gaseous source - such as Liquid Petroleum Gas (LPG). The amount of LPG introduced is determined by the need to enable enough LPG to be added into the air stream, such that when ignited a predetermined preferred heated air temperature is 11 achieved. If too much LPG is added, the LPG can vent out and ignition of the gas is compromised. Accordingly, the ratio of air to gas is important. The speed of the air blower is adjusted such that the air mixes with the LPG source to effect a ratio of air:gas mix where the oxygen content is less than 2%. 5 Accordingly, an oxygen reduced atmosphere or normal air may be used for the airflows required in undertaking the method/process of calcining as provided by the present invention. The air is heated by the inclusion of an ignition source. The ignition source is located in the vicinity of entry of the air (and LPG) into the chamber. The ignition source ignites the LPG mixed with the air/reduced oxygen flow. 10 The ignition source, and the air and the flammable gas delivery are localised within a firebox at the lower distal end of the vertical chamber. In addition, the firebox may have included or associated in the vicinity thereof, nozzles or similar means to inject water into the flame created by the ignited LPG:air mixture. Both the air and water may be introduced at this point in predetermined amounts as regulated and 15 monitored by monitoring means, such as gauges. The rate set is based on a litre per minute and the air:water combination is set to the required pressure such that when entering the flame in the firebox, the air and water creates a mist. The heat from the flame transforms the mist into steam. The steam and the heated air rises up the inner cavity of the chamber. The use of steam in the process air allows better heat transfer to the particles of phosphate rock 20 introduced into the chamber. As the heat rises, temperature sensors associated with the chamber detect the intensity of the heat as it rises up the centre of the chamber. The temperature sensors enable the heat to be regulated by controlling the LPG/air mixture. If more heat is required, then more LPG/air is introduced. If less heat is required, less LPG/air is introduced. 25 At all times, the level of oxygen is also monitored. This is preferred to maintain a reduced oxygen environment. Steam is used to aid removal of the cadmium from phosphate rock particles. Steam is used to "pick up" the vapourised cadmium. 12 Steam acts as a catalyst in the reaction. The steam is later vented and condensed along with the cadmium in a collection step. The cadmium is subsequently obtained by cooling the steam to form water, then removing the water from the cadmium. 5 In addition to the heated air travelling up the inner cavity of the chamber, there is also preferably included within the chamber, an inner centrally located tube. The inner tube operates as an inner chamber within the main chamber and is preferably centrally located. The tube includes an opening located in the vicinity of the generation of the heated air. Heated air is able to enter the inner tube of the chamber under pressure and travels up the inner tube. 10 Heated air exiting the inner tube is directed from the chamber, via a connecting pipe, to at least one secondary chamber. Said secondary chamber is adapted to be and/or include the centrifugal means. In preferred embodiments of the present invention, the calcining apparatus includes at least one centrifugal means. Multiple centrifugal means may be included within the calcining apparatus. 15 Any of various centrifugal devices may be included for a range of purposes, including but not necessarily limited to the separation of materials-such as solid rock particles from the gases/air used during the flash calcining process. For ease of reference, the centrifugal means shall now be referred to as a cyclone system. However, it should be appreciated that use of this term is not intended to be limiting. Rather, the cyclone system will extend to a range of means adapted 20 to create a vortex or other means that assists in the separation of the rock particles and the gases within the calcining apparatus - and may be located at varying locations within or associated with the apparatus/the process. The cyclone system preferably includes sensors located at or associated with an output venting point - being adapted to measure the oxygen/gas vented therefrom. 25 The cyclone system is driven by the heated air. The cyclone system is also adapted to deliver the warm air into the motor driven auger which carries the finely ground phosphate rock particles towards an entry point into the chamber. At the point of re-entry of the very fine phosphate particles to the auger system, there is effectively created a venture which further draws the fine particles back into the process. 13 Accordingly, a predetermined amount of air, heated to a predetermined temperature is available to pre-heat the finely ground phosphate rock before it enters the chamber. The pre-heating of the phosphate rock particle source is a beneficial aspect of the present invention as it assists with the process of slowly heating the finely ground phosphate rock particles, which in turn is a 5 stage which improves efficiency of the process. The phosphate rock particle feed is introduced towards the upper end of the chamber. Accordingly, the finely ground RPR particles are introduced into the first chamber such that the particles begin to fall due to the effects of gravity. Conversely, the heated airflow with, or without added water converted to steam is introduced towards the lower end of the chamber. 10 As the phosphate rock particles fall they contact the heated air/steam flow and are carried by that flow within the chamber. The residence time of the RPR particles within the first chamber is subsequently determined and increased by the tangential path the particles follow through the vertical chamber as a result of the airflows carrying and buffeting it. The rate of entry of the phosphate rock particles into the chamber is undertaken as 15 predetermined to achieve optimum outputs from the process. This is achieved in part by the speed of the variable speed drive powering the auger delivery means. In addition, at the point of entry of the finely ground phosphate particles from the hopper to the auger system, there is effectively created a venturi which further draws the particles into the process. The speed of the auger will hence dictate the both the quantity of phosphate rock dragged into the auger system 20 and speed at which the phosphate rock particles are fed into the chamber. In addition, to further assist entry of the phosphate rock particles from the hopper into the chamber, the hopper/feeder tank is preferably pressurised. The pressurised feeder tank actively therefore introduced the phosphate rock to the input entry of the chamber. Preferably, the feed source is pressurised to overcome resistance to its entry into the chamber due to the airflows 25 within the chamber. The pressure in the hopper/feeder tank is preferably at the same pressure as the pressure within the auger system. For example, in one embodiment, 2kg per hour of finely ground phosphate rock particles may be introduced in to the chamber. It should be appreciated the quantity and speed of input may 30 be determined by a number of factors, including the scale of the apparatus. 14 Additional heating means, such as heating elements are preferably also associated with the chamber. The additional heating elements may be located around the chamber circumference and within or around the central internal tube located within the chamber. The phosphate rock particles are carried towards the heat by the heated air. The particles are thereby slowly heated, 5 not shock-heated. The first chamber is adapted to allow the upward rising, air to swirl and pass through sections of increasing and decreasing diameter sections of the inner chamber. As the air passes through the narrower sections, the air effectively surges. Then, as the air and particles enter a section of the chamber with increased interior diameter, the rising air is then slowed down by the 10 expansion that takes place and the further distance the air has to swirl around when it reaches the sections having an increased chamber diameter. As a result of the configuration of the chamber, the distance travelled by the phosphate rock particles carried by the heated air within the chamber may amount to many times the length of the chamber itself. For example, where the chamber may be in the vicinity of three meters 15 high, the particles may however travel a distance of 20 meters or more due to the swirling air and the residence time within the chamber. As may be appreciated, the distance travelled by the particles would be increased by any one or more of the length of the chamber, the number of sections of increasing or decreasing diameter, the temperature, the airflow pressure, and so forth. 20 The phosphate rock particles carried by the air into the inner heating chamber are forced outward by centripetal force. As these particles spiral through the inner chamber they experience resistance when coming into contact with the inner lining of the inner heating chamber. The result is that the bottom portion of the particle mass slows down allowing the top portion of the particles to move over the top. In this way fresh PR particle surfaces are 25 constantly exposed to heat improving overall cadmium removal and heat efficiency. As the finely ground phosphate rock product moves through in the airflow the particles encounter resistance on the bottom and the top is pushed over in effect rotating the particles and exposing more surfaces. Vanes, or similarly configured projections, located on and projecting from the internal surface 30 of the lining and into the interior of the chamber may be included to deflect the particles 15 thereby keeping the particles. This is preferred to minimise the likelihood of the particles away from the inner lining of the inner heating chamber and thereby reduce the contact between the particles and the heated surfaces. It is preferable that the particles are slowly and indirectly heated within the chamber, as opposed to being shock-heated from contacting the high 5 temperature internal surfaces. In preferred embodiments of the present invention, the deflector means/vanes projecting into the interior void of the chamber in effect contribute to/facilitate the swirling of the rising air and entrained particles thereby increasing the particles' overall residence time. The wider sections of the chamber effectively slow down movement and increases the 10 residence time of the particles suspended by the air in that section. As the movement of the particles is slowed, the effect of the otherwise abrasive characteristic of the phosphate particles against the interior lining of the chamber is reduced. The operation of the apparatus and hence the method of improving the removal of cadmium content from finely ground phosphate rock particles is due in part, to the long residence time of 15 the phosphate rock particles within the calcining apparatus and those phosphate rock particles being exposed to heat inside the calcining heated chamber. In other embodiments of the present invention the apparatus may be adapted to include other features and ways to increase the rock particle residence time. Spinners may also be included within the chamber to direct the movement of the heated air and 20 maintain the swirling airflow to ensure the particles of phosphate rock are constantly exposed to even heating and retained residence time. In other uses of the present invention, for different types of rock, the calcining apparatus can be finely controlled so that the residence time of the finely ground rock particles can be accurately varied for the said different types of rock. 25 The slow residence time enables slow heating of the phosphate rock particles. This is a potentially realisable advantage as the apatite structure in the RPR is least disturbed. The heat is transferred into the finely ground phosphate rock particles via the heated air and steam. There is no direct heat applied to the phosphate rock particles and they are not directly exposed to any flame of heating elements or so forth. 16 Vapourised cadmium separates from the finely ground RPR/Phosphate rock particles rise with the airflow. The cadmium is released as a vapour. As this occurs, the RPR particles fall and the cadmium rises in the steam. The cadmium in vapourised form can be separated out by steam (to which it attached), or it is scrubbed out using high intensity scrubbing after the air leaves the 5 apparatus at a final cyclone stage. The heated air from the chamber is similarly carried (as was the heated air carried up the inner tube in the middle of the chamber) to the centrifugal means/cyclone system, which is effectively configured as a secondary chamber. This air is then subjected to the centrifugal effect and any ultrafine phosphate rock particles, carried as dust up and out of the chamber are 10 able to be stripped from the air and fed back into the calcination process, via the auger system, in the same way the heated air is returned to the system to pre-heat the phosphate rock particle being fed from the hopper into the chamber. In other embodiments of the present invention, the pre-heating of the rock particles prior to entry into the chamber may be preferable where other rock requires even higher processing 15 temperatures. The pre-heating effectively speeds up the process and means less external heat needs to be applied. As such the system recycles what would otherwise be waste heat at the end of the process and provides a method that is more energy efficient. Over time, the phosphate rock particles within the chamber slowly fall down to the lower end of the chamber. At the base of the calcining chamber the RPR falls into collecting means. In 20 one embodiment of the present invention, the collecting means is a fluid bed. Below the fluid bed, fresh cold air and/or cooler air from the heat exchanger and, if required, water are introduced. The incoming air and water cool the phosphate rock particles in the fluid bed. The hot phosphate rock in the fluid bed heats the incoming air and water and the heat forms steam to act as an additional catalyst in the reaction to effect the cadmium removal from 25 the phosphate rock particles and to act as a carrier for the cadmium once it is removed. The depth of the fluid bed is able to be varied to control residence time. Cadmium is carried out of the chamber in the steam and air flow. The cadmium is removed by either intensive water scrubbing or by condensing the steam used in the chamber then evaporating water off under vacuum. 17 A further cyclone system may be included at the lower end of the chamber configuration at or adjacent to the point where the finely ground heated phosphate rock particles drop from the chamber towards the collecting means/fluid bed. At this point, or even at the point of exit of the steam and cadmium from the upper end of the chamber, the temperature may be above the 5 volatisation temperature for removal of cadmium. As such, the temperature may be in the vicinity of 800 degrees Celsius. When the particles in hot air at a temperature in the vicinity of 800 degrees Celsius are hot by a cold mist of water, the water effectively operates to scrub the cadmium from the particles. The effect is determined by the heat of the particles and the volume of water per minute applied 10 thereto. For example, the water may be applied at a rate of 2 litres per minute. When the water hits the particles, the cadmium drops out. The misters introducing water and added in the vicinity of the collecting means for the phosphate rock particles may further assist the process. As mentioned above, any additional cadmium may be carried by the steam and heated air to be transported up and out of the 15 chamber; while the particles of phosphate rock drop towards the collecting means. In other embodiments of the present invention there may be multiple fluid beds in a single chamber. Each bed heats at a different temperature with the beds getting hotter progressively. While a single bed may heat immediately to a required temperature, multiple beds ensure slow gentle heating. 20 Cadmium removal in a reduced oxygen atmosphere is more effective than other flash calcining methods. This method incorporates a simple electrical means of adding heat to the chamber. Using electricity in combination with the burning fuels at the ignition site, means more RPR phosphate rock product may be heated for a lesser airflow. This is because less air has to be heated. In one other embodiment of the present invention, a variation to the above described 25 apparatus and process is that the firebox and burner fuel source is introduced just above the fluid bed. In this embodiment, the heat of the fluid bed provides the ignition source for the fuel/gas at the ignition site within the firebox. The chamber is also designed to be operated under pressure or under vacuum. As regards the use of a vacuum in the calcination process, it is understood that a vacuum calcine has not been 30 used before in the removal of cadmium from RPR/phosphate rock. 18 When a vacuum is used, lower temperatures can also be used to release the cadmium from the finely ground RPR. In flash calcining under vacuum at a lower temperature, it is suggested that heat is "pulled" by the vacuum into the bulk mass of the phosphate rock particles through fine cracks and fissures thereby more efficiently calcining the particles and enabling the cadmium to 5 be removed. A potentially realisable advantage of flash calcining under vacuum is that lower temperatures result in lower plant/apparatus capital costs, lower energy inputs and less damage to the RPR crystal structure. All of these things are able to be accomplished in the single chamber. 10 The single chamber is simple and cheap to construct and the walls will receive very little if any abrasion from the abrasive reactive phosphate rock or phosphate rock due to the slow speed of travel of the rock particles carried by the swirling airflow/steam. It is a low cost eloquent solution for the removal of cadmium from phosphate rock. The single chamber can be easily extended or reduced in height by the addition or subtraction 15 of modular chambers having sections of increasing and decreasing internal diameters. The flash calcining apparatus of the present invention is able to use electricity and/or other fuel sources such as oil, coal, sawdust, biomass materials and gas. Extra heat provided, either by burning gas or using electricity generated heat, may be used to increase capacity. In addition, the apparatus is adapted to use one than one energy source and as such this is able 20 to be built into the apparatus/a single plant. For example a combination of electricity and gas may be used; or alternatively, a combination of oil/gas and electricity may be used. The use of oil/gas during peak demand electricity hours reduces overall energy costs. Cheaper electricity can be used during non-peak demand hours. One of the benefits of using electricity is lower CO 2 emissions. In addition, it is cleaner and 25 easier to use. Also, less air has to be heated, thereby improving the economy of the process. It is proposed that the present invention may be adapted to make use of electricity generated by a variety of available generation means, such as generation from windmills/wind turbines 19 thereby being able to maximise power generated via such systems in off-peak electricity demand times. Having the ability to either or both burn fuels and use alternately generated electricity, means that where a cheaper source of generated electricity is available, the use of organic fuels burnt 5 is able to be reduced and is another beneficial aspect of the present invention as it applies to the extraction of cadmium. A major benefit of this type of plant using electricity for the bulk of the heating is a reduction in the overall carbon footprint in comparison to a plant burning fuels alone. The ability to pre-heat all or part of the apparatus enables immediate operation of the apparatus 10 for the calcining process becomes more favourable when off-peak demand electricity becomes available. It is also means that it is possible to vary production rates according to the amount of off-peak power available. The use of electricity enables elements and heating tapes to also be placed on or around the 15 calcining apparatus and be used therewith to add heat in to the process at separate stages along the heating path and thereby gradually build up to the calcining temperature required of between 600 0 C and 1200 0 C. This effectively minimises disruption of the crystalline apatite structure of the phosphate rock. Cadmium removal via the method of the present invention is achieved by either or both 20 condensing steam introduced into the calcining chamber and scrubbing the out-going air using an intensive scrubber, then evaporating the water thus leaving behind the cadmium and other heavy metals as a residue to be easily disposed of. As part of this invention the finer particles are granulated after the removal of the cadmium. It is here that the process is designed to be heat efficient. Once the cadmium has been removed 25 the RPR is cooled to 90 degrees Celsius then pelletised. The temperature of the RPR in the granule dries off the water binder and the process heat is used in the granulation process. The heated RPR particles can therefore be granulated and dried without the need the additional heat. The following are features associated with, or adapted to be associated with, embodiments of the present invention. Accordingly, the apparatus and process may include any combination of 20 the following features to achieve optimum efficiency and preferred, predetermined operation and outcomes: * At least one burner, for effecting a reduced oxygen atmosphere. Preferably, the burner is a gas burner. Extra burners can be included as required. 5 e The burner is used to generate a flame. The flame is required to achieve optimum 02 in the chamber atmosphere. As such, the flame is preferably adjustable. When an electrically generated heating source is also being used to provide the heat supply required for the process, a reduced flame is still able to be used as it continues to produce a reduced oxygen atmosphere. 10 0 One or more electric heating elements (capable of heating up to 1500 0 C) for use in heating the product in the chamber. * The option for the apparatus to operate under vacuum. * High velocity, high load air/product flows. This enables a low air volume to be used. Accordingly, a lower air volume is subsequently required to be made into a reducing 15 atmosphere thereby reducing carbon emissions. More specifically, the following features of the apparatus provide additional benefits in the operation of the apparatus and the outcomes derived from the method of the present invention: * The inclusion of a heating element - such as a heating bar located at anyone or more of down the centre and/or around and/or down the sides of the chamber is a potentially 20 beneficial improvement. For example, heat is then able to radiate out from the heating element(s)/bar(s) and also inwards from the electrical heating of the ceramic walls of the main chamber. * Low velocity and low airflow reduces heating costs. * Vanes are placed at the entrance to the main heating chamber and/or within the 25 chamber - to cause the air to spin. This has the effect of increasing overall residence time of the finely ground phosphate rock particles within the chamber. * The speed of the air going up the heating chamber determines the residence time. This speed can be measured and adjusted. * The plant is vertical in orientation. 30 e The slow movement of product will lead to lower abrasion of the plant internals. * It is possible to increase plant capacity by increasing heat the applied. 21 Further features of the present invention which singularly and/or collectively contribute to the unique method and apparatus of the present invention and are of particular significance, include any one or more of: 1. The use of finely ground phosphate rock. 5 2. The use of steam as may be advantageous in some embodiments. 3. The use of spinners/vanes. 4. The use of lime in the calcinations process. 5. The process for collecting the removed cadmium. 6. The use of improved apparatus enabling indirect heating in the calcinations process. 10 7. The use of faster airflow, such that it results in an increased "stripping" effect in the removal of the cadmium from the phosphate rock particles. 8. The ability to use and control the use of pressure and vacuum within the circuit. 9. The use of progressive heating. 10. The energy efficient options employed by the present method and/or resulting from the 15 design of the apparatus. 11. The ability to take advantage of characteristics of the end-product treated phosphate rock exiting the apparatus after removal of the cadmium, to facilitate improved production of a granular fertiliser product. Having regard to the use of finely ground phosphate rock, the method of reducing the cadmium 20 content of phosphate rock is effected by the phosphate rock preferably and initially being pre ground to smaller particle sizes. Preferably, the phosphate rock is pre-ground to particles less than 150 micron in size. Preferably, the phosphate rock is pre-ground to particles typically less than and 75 microns. Preferably, the phosphate rock is pre-ground to particles typically less than 45 microns. 25 Potentially realisable advantages flowing from pre-grinding the phosphate rock to such finer particles is associated with the fact that the finer particles have an exponentially higher surface area. This provides advantages as it results in, provides and/or requires: * Shorter residence times. * Lower cadmium volatising temperatures. 22 * Greater surface exposed to steam and higher reactivity caused by phosphoric acid being formed on fine particles. * When an acid is introduced to the steam a greater reactivity can be achieved as acidic steam achieves action over a larger surface area of the phosphate rock particles. 5 * Smaller particles expose more of the cadmium, therein, directly to the heat. * The use of fine particles reduces the amount of pressure the volatised cadmium requires to exit from inside the phosphate rock particle. * Finer particles, which can be calcined at lower temperatures, are significantly less likely to sustain structural damage and loss of reactivity. 10 0 Finer particles can be heated more gently as the heat transfer to particle rate is greatly improved. * Finer particles when applied to the soil are more reactive. * The use of less reactive phosphate rocks, from varying phosphate rock sources, will be possible as the process substantially assists by overcoming any loss in reactivity due to 15 heat treatment. * Finer and therefore more reactive particles are more suitable for colder climates. Having regard to the use of steam in preferred embodiments of the present invention, steam is used to specifically assist in the removal of cadmium. The benefits of steam are that it opens up the structure of the phosphate rock and that it mixes 20 with the cadmium as it vaporises, thereby facilitating removal of the cadmium from the phosphate rock. This will also have the benefit of lowering the temperature required to remove the cadmium. Steam enables improved contact between the phosphate rock particles and the heat, resulting in lower calcining temperatures and may contribute to higher removal efficiencies. 25 Using steam also preferably results in less structural damage to the phosphate rock. This is because the overall calcining temperature is lower than when using heated air alone. The phosphate rock will not fuse or harden using this calcining process. Where steam is used, the steam is able to be introduced anywhere in the circuit, but preferably and specifically at the following places within the calcining process and apparatus locations. 30 1. At the flame generated in the firebox. 23 2. At the product feed entrance where the steam will encounter the product at increased velocity. 3. As a result of using product pre-dampened prior to introduction to the process, in order to give "instant steam" within the phosphate rock structure. 5 When steam is introduced at the flame this enables improved heat transfer between the inner chamber/tube and the outer chamber. A potentially realisable advantage of steam contacting the phosphate rock particles is that the steam may become mildly acidified via the formation of phosphoric acid. This phosphoric acid/steam mixture then acidulates the phosphate rock thereby improving its reactivity. This 10 will assist in overcoming and addressing the loss of reactivity due to heat treatment in existing calcining processes. Partially acidulated phosphate rocks are more reactive and it results in a product especially suitable in cold environments. Another preferred alternative to the description above is where the process steam is acidified 15 before introduction to the circuit. This enables a degree of control over the reactivity of the final product. In this latter case it is preferable that an online/in-line pH meter be used to control this process. The use of steam in the present invention also has the additional benefit of breaking up particles, thereby maximising heat transfer and may contribute to calcination efficiency. 20 Having regard to the use of spinners in accordance with the embodiments of the present invention, it is to be noted that when the airflow is spinning down the inner heating chamber the tangential forces will typically decrease as the air and product move down the chamber. In order to minimise this effect spinners supported by the inner tube are placed at various points inside the inner heating chamber. 25 The use of spinners provides the following benefits in that the spinners: * Increase the air velocity, to rip cadmium vapour from the phosphate rock particles. * Decrease the tangential angle of the airflow increasing the velocity of the air. This results in greater centripetal forces resulting in increased contact between the phosphate rock particles/product and the heated walls of the inner chamber. 24 * Enable the increased tangential angle and faster airflow to assist in the cyclonic separation of the phosphate rock product from the airflow. This results in less fines travelling up the gas outflow tube. * Contribute to the coarser phosphate rock particles/product (which requires more heating) 5 being thrown out further into the hottest zones at the walls of the inner heating chamber. * Improve increased airflow that results in a better cut of the phosphate rock particles/product at the cyclone. * The spinners are used to centre the gas outlet tube and prevent distortion. In addition, the spinners are not attached to the outer chamber wall. Therefore, this allows the 10 central/inner gas outlet tube, within the chamber, to grow and shrink as it is heated. As regards the use of lime in the calcinations process, it is to be noted that by incorporating limestone (CaCo 3 ) into the phosphate rock feedstock introduced for calcination, carbon dioxide will be produced as a bi-product, during the calcination process. Carbon dioxide production is potentially advantageous as its presence further contributes to the inert atmosphere in the 15 circuit, thereby improving cadmium removal efficiency. Calcined lime is also a desirable fertiliser. The calcined lime also preferably acts as a pH neutralising agent, particularly where phosphoric acid is formed due to the use of steam in the process. Having regard to the process of collecting the separated cadmium resulting from the method 20 employed, the cadmium is removed by condensing the steam and heating off the resultant water using waste process heat, thereby leaving the cadmium waste product. A potentially realisable advantage of the present invention is achieved by making use of waste heat from the process to drive the separation of water from the collected cadmium, thereby reducing the demand for energy from other sources as would otherwise be required to 25 undertake the separation process. This offers substantial cost benefits by reusing a heat supply that would otherwise be vented as waste heat. Having regard to the improved apparatus enabling the use of indirect heating in the calcinations process, it is to be noted that for the purpose of removing cadmium this circuit is unique in that the final heating cyclone is much longer than normal and the outer wall of the inner heating 25 chamber is heated - effecting indirect heating. This indirect heating stage in the apparatus and method design is novel, particularly where designed for cadmium removal. As regards the increased "stripping" effect of cadmium from the phosphate rock particles, the design of the apparatus and the flow resistant properties of the particles effect the situation 5 whereby the airflow is substantially faster than the product flow. The faster airflow enables the volatised cadmium to be more efficiently removed with the heated air in advance of the treated phosphate rock product reaching the cyclone stage of the process/apparatus where it then cools and is collected. The circuit is preferably configured to allow for air speed changes in order to enhance the 10 cadmium stripping effect. This is achieved by changes in ducting/chamber diameter and the use of spinners (as discussed previously, above). As regards the pressure or vacuum feature of the present invention, it is to be noted that the present invention, in terms of the method and apparatus, may be operated under pressure or under vacuum. The pressures and vacuum are preferably controlled within the process circuit. 15 In addition, the present invention utilises progressive heating as a feature in the methodology and during operation of the apparatus. A potentially realisable advantage of this feature is that progressive heating uses heat more efficiently. The present invention also benefits from consideration of aspects of the apparatus and process that are substantially energy efficient. For example, the method of cadmium removal of the 20 present invention is able to achieve lower overall energy costs due to the use of: * Fine phosphate rock particles * Steam * Preheated phosphate rock product. As regards the aspect of granulation of the calcined phosphate rock, the fine particles resulting 25 from grinding the phosphate rock initially prior to treatment to achieve improved removal of cadmium from the phosphate rock, also means that the fine particles can be more easily made into granules. This is able to be achieved often with water alone as a binder. Preferably, as part of the process the treated phosphate rock product will be granulated while still retaining heat from passing through the treatment process. 26 A potentially realisable advantage of this stage is that the granules may be made more quickly and directly following completion of the treatment process. In addition, achieving granulation while the treated phosphate rock product still retains heat from passing through the treatment process means it make a subsequent stage of drying the granule unnecessary. Not only does 5 this provide a time/cost benefit as the granulation process is completed more quickly, but it also provides a cost benefit as the need for additional heating (energy costs and sources) or equipment (ovens, drying racks, etc) to dry the granules is minimised or avoided. The plant is designed specifically to remove cadmium from Reactive Phosphate Rock (RPR) or Phosphate Rock (PR). However the apparatus and method/process can be used for, or adapted 10 for use for, other applications. The apparatus and method/process are simply described herein as used with RPR and/or PR to explain the various features of the apparatus, the stages of the process, the characteristics of the final products so produced and some of the potentially realisable advantages achievable with the present invention. As will be appreciated, this invention is directed to provide an improved method for a rock 15 treatment process, where the treatment process or method is exampled by a method for reducing the cadmium content of phosphate rock. In addition, the rock treatment process of this invention is further directed to providing a substantially improved apparatus to facilitate a rock treatment process as exampled by the method for treating phosphate rock and reducing the cadmium content of the phosphate rock. 20 The apparatus and method enable the improved production of a treated phosphate rock product having reduced cadmium content yet with retained reactivity. Further, the method results in treated phosphate rock particles that have an increased surface area. The increased surface area is not only due to the fine grinding of the phosphate rock prior to initiating the calcination process, but also to the removal of the cadmium - effectively 25 producing a zeolite structure. Accordingly, the present invention is directed to the then subsequent use of the treated rock, as exampled by use of the phosphate rock, with reduced cadmium content, for the subsequent production of soil treatment fertiliser products. 27 Further, the invention is directed to the use of the treated rock in the manufacture of a soil treatment fertiliser product manufactured in granular form- as exampled by the manufacture of granules formed from and/or including the treated phosphate rock for improved optimal delivery of the phosphate into and on to the soil as well as for improved application, storage 5 and transportation of the fertiliser product. As such the present invention includes stages which encompass both grinding and pelletising of the rock material in original and treated form, respectively. The soil treatment composition so produced is preferably directed to improving soil condition and/or soil-nutrient availability for plants. 10 The term "treatment" as used in this specification with reference to soil treatment, will typically involve a knowledge of the condition of the soil (preferably via prior analysis) and involve administration to the soil, via one or a regimen of applications, a particular preferred composition which aids in improving at least the soil condition (including structure) and/or soil nutrient content. 15 Preferably, the soil treatment composition is provided in granule form for application to soils. The granular product includes one or more of the following features: a) Is, or may be adapted to be, a controlled release granule formulated for a specific soil type. b) Is, or is adapted to be, comprised of components having one or more of a preferred 20 particle size, preferred particle distribution, preferred particle surface area. c) Includes component(s) directed to a specific treatment, specific soil type, specific climatic conditions. d) May includes a component that facilitates dispersal of the granule in water. e) May includes a component contributing to the binding of the components. 25 f) May includes a component that facilitates rapid release of at least one other component from the granule. g) May be uniform in size. h) Is substantially dust free for improved handling, spreading, transportation and safety. i) Is optionally colour coded to ensure correct formulation application to particular soil 30 types. j) Is an improvement on products prone to leaching. 28 k) Granules are not easily separated during a mix. 1) Is a product which can be adapted for preferred timed release for optimum results - such as the speed of availability of nutrients to plants. m) A product which is adapted to address some environmental concerns existing as a result 5 of the use of traditional chemical fertilisers. Preferably, the granule is able to be adapted to be specifically tailor-made in respect of the particle distribution of its components to suit various applications, soil and climatic conditions (including temperature) as required. The granule may have varying composition depending on the components of the granule and 10 the application it is designed for. Preferably, the granule is able to be adapted to be specifically tailor-made in respect of particle size and/or surface area of its components to suit various applications, soil and climatic conditions (including temperature) as required. The granule may have varying particle sizes within its composition depending on the components of the granule and the application it is 15 designed for. Preferably, the particle size is optimised by fine-grinding to suit differing soil conditions and the purpose for which it is being used. Preferably, the granule components are such that the granule components are selected to be able to be tailor made to suit specific soil types in particular countries and for particular soil types in 20 particular regions within said countries. Preferably, the granule, following application, is required to make the components of the granule available within or on the soil. To achieve this, the granule preferably disperses at a preferred rate. The rate of dispersion is pre-determined by the soil components, agents and additives, but also by the grinding and pressing method of the present invention. 25 Preferably the dispersion of the granule enables the components of the granule to be available. However, the individual components of the granule may vary in the rate at which each will be directly available for the specific need. For example one component may be immediately available for use - whether as a nutrient or soil conditioner; whilst others may be released in the 29 soil over time, or at different rates, or with the onset of particular climatic or soil temperature/conditions as required. In addition, the granule form avoids the limitations of traditional mixed fertilisers which are in powdered or loose form. Such fertilisers are typically transported at some stage. The 5 vibrations generated during transportation can cause the different component nutrients to separate out due to their varying densities. When the fertiliser is then applied there is the potential for uneven distribution of the components of the fertiliser and so some areas may remain or may result in being more deficient in a particular component when compared to another. 10 Further, the granule is formed from materials which have been treated to reduce or substantially eliminate toxic elements, thereby effecting a product which is more environmentally suited to reduce/minimise the build up of toxic materials in ecosystems and food chains. It will therefore be appreciated that the invention broadly consists in the parts, elements and features described in this specification, and is deemed to include any equivalents known in the 15 art which, if substituted for the prescribed integers, would not materially alter the substance of the invention. Variations to the invention may be desirable depending on the applications with which it is to be used. Regard would of course be had to effecting the desired particle size(s) of the fertiliser/soil treatment components and so forth. 20 In addition, the pressing of the components into granular form will pre-determine rates of delivery of the soil components and so forth dispersing into and on to the soil. Concentrations or volume to volume ratios of the components of the granule, the various components of the granules, the dimensions of the granule, the dissolution rates, the method of application of the granules and so forth may all be varied as required to effect the desired 25 outcome. Whilst some varying embodiments of the present invention have been described above and are to be yet exampled, it should further be appreciated different embodiments, uses, and applications of the present invention also exist. Further embodiments of the present invention will now be given by way of example only, to help better describe and define the present 30 invention. However, describing the specified embodiments should not be seen as limiting the scope of this invention. Brief Description of Drawings Further aspects of the present invention will become apparent from the following description, 5 given by way of example only and with reference to the accompanying drawings in which: Figure 1 is a diagrammatic representation of an embodiment of a calcining apparatus, in accordance with one embodiment of the present invention; and Figure 2 is a table in which the results of RPR following the calcining process is more reactive particularly when the RPR is ground to fine particle size, in accordance 10 with another embodiment of the present invention; and Figure 3 is a table in which shows the effect of lowering oxygen levels, in a calcining process existing in the prior art to be compared with results achieved in accordance with the present invention; and Figure 4 is a diagrammatic representation of an embodiment of a calcining apparatus, in 15 accordance with another embodiment of the present invention; and Figure 5 is a diagrammatic representation of a preheating system incorporated into the calcining apparatus, in accordance with another embodiment of the present invention; and Figure 6 is a further diagrammatic representation of a preheating system incorporated 20 into the calcining apparatus, in accordance with another embodiment of the present invention; and Figure 7 is a table in which the results illustrate oxygen reduction achieved by use of two reducing catalysts within the calcining apparatus, in accordance with another embodiment of the present invention; and 25 Figure 8 are tables showing the percentage of Cadmium removed relative to the percentage oxygen levels (reduced) during operation of the calcining apparatus in accordance with another embodiment of the present invention; and 31 Figure 9 is a table in which the results illustrate the effect of temperature (in 'C) on the percentage of cadmium removed from calcined RPR during operation of the calcining apparatus in accordance with another embodiment of the present invention; and 5 Figure 10 is a table in which the results illustrate the percentage of cadmium removed from calcined RPR during operation of the calcining apparatus in accordance with another embodiment of the present invention; and Figure 11 is a table in which the results illustrate the effect of temperature (in 'C) on the reactivity of calcined RPR effected during removal of cadmium from RPR 10 during operation of the calcining apparatus in accordance with another embodiment of the present invention; and Figure 12 is a table in which the results illustrate the optimum temperature required to efficiently remove cadmium from RPR during operation of the calcining apparatus in accordance with another embodiment of the present invention; and 15 Figure 13 is a diagrammatic representation of a further embodiment of calcining apparatus, in accordance with one embodiment of the present invention. Best Modes for Carrving Out the Invention With reference to Figures 1-13 and the described examples of the present invention, there is provided an improved calcining method and apparata used therewith. 20 Particularly, the present invention is directed to improved rock treatment processes. Accordingly, in one embodiment, the invention is specifically directed for use with reactive phosphate rock (RPR) and phosphate rock (PR). Further, a specific embodiment is directed to a rock treatment process for reducing the cadmium content of RPR and phosphate rock that is able to subsequently produce a treated 25 phosphate rock product with reduced cadmium levels and yet retained reactivity. There are two types of phosphate rock: 1. Reactive Phosphate Rock - capable of passing the citric acid test. 32 2. Phosphate Rock - used for production of superphosphate via sulphuric or phosphoric acid methods. Reactive rock phosphate (RPR) is an alternative phosphate fertiliser to superphosphate. There are many grades of rock phosphate available around the world. The agronomic value of rock 5 phosphate is dependent on the following parameters: total phosphorus pentoxide (P 2 0 5 ) content, particle size distribution, and solubility. Solubility and hence the rate of reactivity in the soil is measured by tests known in the prior art, such as the 2% citric acid test. If the solubility of the phosphorus in a phosphate rock in the citric acid laboratory test is at least 30% of the total, such a product is labelled a 'Reactive 10 Phosphate Rock', and the majority will have typically become plant available within two years of application. Solubility can also be measured as percentage phosphorus pentoxide (% P 2 0 5 ). In this case a figure of >9.4 (soluble P 2 0 5 as a percentage of the rock phosphate) indicates a reactive rock phosphate. 15 The present invention is directed to the use of the phosphate rock, with reduced cadmium content, in the production of soil treatment fertiliser products. The present invention is anticipated to provide consumers with a fertiliser product that is a substantial improvement over existing reactive phosphate rock and phosphate rock fertiliser products that have not had the cadmium removed at all, or to any substantially acceptable 20 extent. In addition, the invention is further directed to the use of the phosphate product in the manufacture of a soil treatment fertiliser product produced in granular form for improved optimal delivery of the phosphate into the soil as well as for improved application, storage and transportation of the fertiliser product. 25 It should however, be appreciated that the following examples, while relating to one embodiment of the invention directed to removal of cadmium from RPR and PR, should not be seen as limiting the present invention. The method and apparatus may be similarly used with, or adapted for use in flash calcining other materials. 33 EXAMPLE 1 The method of manufacture uses fine particles in a flash calcining process primarily to remove cadmium from Phosphate Rock (PR) source material and also from Reactive Phosphate Rock (RPR) material and to improve the reactivity of Reactive Phosphate Rock (RPR) material, as 5 used for direct application to soils in soil treatments, such as fertilisers. With reference to varying embodiments of the calcining apparatus 1, illustrated in Figures 1, 4 and 13 ambient air is introduced into the firebox/manifold A, via the air inlet (2) immediately prior to the flame (3). The air, or in some embodiments an air/gas mixture, may be supplied from an external source/tank 2a (as shown only in Figure 13). 10 The air is heated by the flame (3) and is drawn through the manifold A, into the outer chamber of the heating reactor (5). Steam (or an atomised water supply), where required for the process, can be introduced at different points in the circuit. 1. In the vicinity of the flame (3) (at entry point B in Figure 1). 15 2. To the product feed entrance where the steam will encounter the product at increased velocity (not shown). 3. Where it is an option for product to be dampened prior to introduction to give "instant steam" within the PR structure (not shown). 4. At any other place in the circuit as required (not shown). 20 In order to maintain a reducing atmosphere, oxygen is kept between 0 and 5%. This may result in the volume of air being too high. Control Taps (shown at 10 in Figure 4 and at 11 in Figure 1) can be used to remove this excess air when required. There are no control taps in the Figure 13 embodiment. The plant is able to operate under vacuum (suction). When this is the case, air suction pumps 25 are employed at Control Tap (10 in Figure 4) and may also be included in the vicinity of the scrubber (14) (the control tap in this vicinity is however not illustrated in Figure 4). The plant can also be operated under pressure. In this case an air pressure pump is used at the air inlet (2) and Control Tap (11 in Figure 1) is used to remove air as required. 34 The process heat generated in the fire box is then exchanged onto the inner reactor chamber (4) walls where it comes into contact with the PR / air / steam process stream. The PR feed is introduced into the circuit at D via the feed hopper (8) and feed auger (9). In Figure 1, the heated air in the outer chamber (5) is able to be drawn to the product feed 5 system (as exampled at C in Figures 1, 4 and 13) where it is utilised to preheat the product. The PR particles are preheated in the heated airflow as they are introduced tangentially and are drawn up into the top of the inner heating chamber (4). The PR then begins to spin inside the walls of the inner heating chamber (4) coming into close contact with the heated walls, but preferably relying on indirect heating. Spinners (not shown in Figure 1, but shown at (25) in 10 Figures 4 and 13) are used in the inner heating chamber (4) to produce a venturi centripetal effect. This effect forces the PR to come into close proximity to the heated chamber walls and the PR is heated in the most efficient manner possible. The larger the PR particles are the closer they will travel to the inner chamber walls. This gives additional heating efficiencies, as the larger sizes need more heat than the smaller particles to volatise cadmium. 15 As the PR is heated above 350 0 C and up to 1000 0 C the cadmium begins volatise from within the PR structure. In Figure 1, the bulk of the PR exits the inner chamber via the cone shaped base of that chamber (15). The cadmium and the ultrafine 1 - 15 micron PR particles exit the inner chamber via the gas outflow tube (6). 20 The gas outflow tube (6) may be connected to: * A cyclone, which removes the PR fines (26). * A steam condenser (14). * A water scrubber (13) One or more of the above may be used in any desired order. 25 The process of removing the calcined PR and removal of the cadmium is not shown in Figure 1. However, a fuller representation of the process is illustrated in Figures 4 and 13; along with Figures 5 and 6. 35 The dimensions of the inner heating chamber and velocity of airflows are critical in ensuring that residence time remains within required limits and to ensure maximum heating efficiency. Other components, agents, additives may be highly water-soluble and so enables the granule to rapidly dissolve when coming into contact with moisture. This characteristic imparts excellent 5 dispersing ability to the granules when applied. Reducing atmosphere A reducing atmosphere prevents the volatised cadmium recombining with the PR as cadmium oxide (CdO), thereby resulting in higher removal efficiencies. Pre-feed Preheating 10 Pre-heating prior to feeding product into the circuit has the following benefits: 1. Increased production rates. 2. Enables larger particles to be used. For example: PR particles can be preheated externally to say 600 0 C and only need an additional 100 0 C temperature increase using the circuit outlined in this brief in order to remove the cadmium. 15 The PR can be preheated in the circuit shown below to 200 - 700 0 C. The PR can also be preheated externally using the circuit shown below from 0 to 800 0 C and introduced at the feeder. This will increase plant capacity. Gas outflow Tube A gas outflow tube is installed down the centre of the inner heating chamber and is used to 20 remove ultrafine material (<1 - 15 micron) and the airflow containing volatised cadmium and steam. Flash calcinin2 temperatures Flash calcining with fine particles can typically occur between 350 and 1 100 0 C. Residence time 25 Control of residence time is critical to prevent sintering the PR with subsequent damage to structure and loss of reactivity. The residence time of the product in the main chamber is 36 approximately 10 seconds and between 1 and 20 seconds. Longer residence times will likely result in the PR becoming sintered and unreactive. Indirect heating PR is preheated and flash-calcined by indirect heat. PR is never exposed directly to the flame 5 reducing the risk of sintering the PR and causing it to become unreactive. This inner heating vessel is heated indirectly and the RPR is heated as it spins against the inside wall of this vessel and by the heat exchange of heated air and steam. At the point the products reaches its highest temperature the product has no direct contact with the flame. 10 Cadmium separation After the PR is removed by cyclone, filter or other methods, the cadmium in the heated steam airflow is to be removed by water scrubbing. Particle extraction Particle extraction from process air is undertaken by means of cyclones, filters or water 15 scrubbers. If required water scrubbers will be used to remove any cadmium not entrapped in the steam. Acidulation Partial acidulation can take place during the heating process. Calcinated PR can also be acidulated later to improve reactivity. 20 Cyclone Cooling As the hot product drops into the cyclone it is cooled when coming into contact with the cool cyclone walls. Progressive heating Progressive heating also utilises heat more efficiently. 37 Reactivity The RPR is more reactive due to the fine particle size. See results in Figure 2. It is known that calcining phosphate rock can lower reactivity through a breakdown of the rock structure. The present process aims to mitigate this effect by the use of finer particles than 5 previously used for cadmium removal which will enable lower calcining temperatures. The process potentially uses the following particle size and temperature ranges: . Particle Size: 10 micron - 2mm. . Temperatures: 200 - 1100 C The phosphate rock reactivity may also be improved by acidulation with acidified steam. 10 Organic Material It is known that for certain phosphate rocks the cadmium can be concentrated in the organic component. This enables removal of a significant proportion of cadmium at temperatures lower than the boiling point of cadmium (950 0 C). For this reason a wider range of temperatures is able to be used in the process of the present invention (see above). 15 OxVen Levels Removal of cadmium is more efficient at lower oxygen levels because volatised cadmium is less likely to combine with oxygen to form cadmium oxide and can therefore be removed as cadmium metal. Figure 3 provides data (source: US Patent - 4017585) shows the effect of lowering 20 the oxygen level from 1.8% to 0.5%. Figure7 provides additional results confirming the operation of the calcining apparatus based on test results relevant to operation of an embodiment exampled in Figure 13. The present invention provides a calcining process that is able to lower the oxygen level below 0.5% and as low as 0%. It is believed oxygen levels lower than 0.5% have not been used 25 previously in cadmium removal processes. The use of highly reducing (<0.5% 02) atmospheres is estimated to improve cadmium removal efficiency up to 98%. The flash process causes less damage to the crystal structure than do slower processes such as fluid bed kiln. 38 With fine particles cadmium is more exposed to the heated air. A larger surface area results in greater cadmium stripping by process air compared with larger particles. As mentioned in the applicant's patent 594880, particles in air travel slower than the air. This results in a stripping type action (clothes the clothesline analogy) which will assist in removing cadmium at lower 5 temperatures. EXAMPLE 1A While much the same as Example 1, minor variations and more detail are provided in Example 1A, which relates to Figure 4. Ambient air is introduced into the manifold via the air inlet (2) immediately prior to the flame 10 (3). The air is heated by the flame (3) and is drawn through the manifold into the outer chamber of the heating reactor (5). Heat is also drawn from the manifold into the Central Heating Tube (11) causing the screw to be heated internally. Heat then radiates out from the outside of the inner chamber. Product is heated by radiated heat. This process heat is then feed back through to the pre-heating chamber 15 at the top of the Central Heating Tube (11). Where steam is introduced, this may be undertaken at: 1. The flame (3). 2. The product feed entrance where the steam will encounter the product at increased velocity (9). 20 3. An option for product to be dampened prior to introduction of the product to the hopper (8) to enable "instant steam" to be generated within the system. Immediately prior to the product feed entrance the air velocity is increased by a restriction or venturi at E. This will provide greater surface contact between the heated airflow (including steam) and the particles. A spinner is placed just after the feed entrance to ensure improve 25 mixing and dispersion of the fine particles in the airflow. In order to maintain reducing atmosphere oxygen is kept between 0% and 5%. This may result in the volume of air being too high. A control tap (10) can be used to remove excess air when required. Areas in the process where the reducing atmosphere is maintained are represented at 02(1) and 02(2). 39 The plant is able to operate under vacuum (suction). When this is the case, an air suction pump may be employed in association with control tap (10) (and also at the scrubber (14) operating later in the process, although a control tap is not shown in Figure 4 at this latter location). The plant can also be operated under pressure. In this case, an air pressure pump is used at the 5 air inlet (2) and a control tap is used to remove air as required. However, this option is not shown in Figure 4. Process heat is then exchanged onto the inner reactor chamber (4) walls where it comes into contact with the PR - air - steam process stream. PR feed is introduced into the circuit at via the feed hopper (8) and feed auger (9). 10 The heated air in the outer chamber (5) is then drawn to the product feed system where it is used to preheat PR product introduced into the pre-heating tube (6) and any PR product introduced into the pre-heating chamber (7). The PR is preheated in the airflow as it is drawn tangentially (simplistically represented diagrammatically at F) up pre-heating tube (6). Spinners (25) are used to ensure maximum heat 15 contact with the particles. The feed particles are then introduced tangentially into the top of the inner heating chamber (4). The PR begins to spin inside the walls of the inner heating chamber (4) coming into close contact with the heated walls. The inner heating chamber (4) consists of a screw (15) which is used to produce a venturi centripetal effect. This effect forces the PR to come into close proximity to the heated chamber 20 walls and the PR is heated in the most efficient manner possible. The larger the PR particles are the closer they will travel to the inner chamber walls. This gives additional heating efficiencies, as the larger sizes need more heat than the smaller particles to volatise cadmium. As the PR is heated above 350 0 C and up to 1000 0 C the cadmium begins volatise from within the PR structure. 25 The bulk of the PR (indicated by arrows 24) then exits the inner chamber via the cyclone (12). The cadmium and the ultrafine 1 - 15 micron PR particles (indicated by arrow 26) exit the inner chamber and are drawn to the scrubber (13) and condenser (14). 40 The residence time of the product in the inner chamber is critical and is controlled by airflow, the pitch of the screw, the dimensions of the inner heating chamber and the dimensions of the central heating tube. These variable parameters are critical in ensuring maximum heating efficiency. 5 Screw The screw (15) consists of continuous fixed spiral - similar to an augur. As the process air and product passes down the spiral it speeds up and centripetal forces cause the particles to move outwards onto the inner walls of the outer heating chamber (5)The screw (15) in the inner heating chamber has a pitch of 75mm and produces a product path length of approximately 15 10 metres. Temperature control Multiple temperature probes are located throughout the calcining apparatus and are marked with a T on the circuit diagram. Accurate temperature measurement will enable the exact volatisation temperature to be determined for a particular product type. 15 Control Taps The control tap (10) enables the airflow to be easily adjusted and accurately controlled. This also allows more or less heat within the circuit. Spinners One or more spinners (25) are used at the following point in the circuit: 20 * Pre-heating chamber (7) * Pre-heating tube (6) * Central heating tube (11) * Outer heating chamber (5) * Inner heating chamber (4) 25 Spinners can be used interchangeably with a screw. Spinners used in the outer heating chamber cause the heated air to spend longer in the chamber thereby increasing contact time with the walls of the inner heating chamber and improving heat 41 transfer efficiency. Spinners are also used in the volatisation zone of the inner heating chamber in order to increase the stripping effect of removing volatised cadmium by increasing air velocity. Air inlet 5 The hot process air is introduced tangentially at the flame (3). The area of maximum heat (H) is located within chamber (5) at or near the junction of the chamber 5 with the firebox A Fines The fine PR particles, air, volatised cadmium (collectively indicated at 26) exit the cyclone (12) at exit point (20) and are carried by the gas outlet tube (16). A single cyclone may be used or 10 clusters of multiple cyclones. Some particles, normally less than 10 microns, will be carried out from the cyclone via the cyclone gas outlet tube (16). These very fine particles of phosphate, volatised cadmium and steam that exit via the cyclone (12) gas outlet tube (16) may be treated further. For example, this stream is passed into a venturi type scrubber (13) using water to scrub the cadmium from the gases. The water 15 containing cadmium and phosphate fines may then be pumped through fine hydrocyclones to recover phosphate fines or passed into a sand screw type device where the phosphate fines settle to the bottom where they are removed by a slowly rotating screw. Another method is to pass the phosphate fines, steam and cadmium stream through a steam condenser (14). The steam condenses to water that also contains the fine phosphate particle 20 and possibly the cadmium. This product is then dropped into a sand screw type device, where the fine phosphate particles settle out and are recovered by a slow turning screw. Or, after condensation the stream is heated to boiling point of water or higher. The fine phosphate particles remain and the stream containing cadmium is then condensed and disposed of. Or, the stream containing cadmium is reheated, the water boils off, leaving the cadmium a as residue. 25 Particle Size As regards the method of flash calcining rock material (including phosphate rock) achieved via use of the calcining apparatus of the present invention, the rock is first finely ground to pre determined particle sizes. The use of fine particles reduces the amount of pressure the volatised cadmium requires to exit from inside the PR particle. 42 Residence Time This invention involves a short retention time (1-20 seconds) in comparison with fluid bed cadmium removal methods. A typical residence time for fluid bed cadmium reduction is 30 minutes. 5 Reducing atmosphere A low oxygen (reducing) atmosphere can be enhanced by inter-calcining limestone with the phosphate. The limestone reacts and converts to calcium oxide. The carbon dioxide produced lowers the oxygen level providing an atmosphere more conducive to cadmium removal. The use of carbon dioxide inerting from lime is important because it allows the kiln to be 10 powered electrically. Off-peak load electricity from wind turbines and other sources can be utilised to provide heat for the process. Product and Gas separation PR product and gas are immediately separated above the volatisation temperature of cadmium by a cyclone (12) placed immediately at the bottom of the central chamber/heating tube (11). 15 Removing particles at this hottest part of the circuit enables accurate temperature control and therefore the particles are precisely heated to the temperature required to remove cadmium to the desired level. Removing cadmium at this point (12) prevents votalised cadmium depositing on any walls of the plant. A condenser (14) and scrubber (13) may be placed in either order or there may be a condenser 20 without scrubber. Product fines will be recovered at this point. Inner Heating Chamber - Screw A screw (15) is installed in the centre of the inner heating chamber to maximise contact between moving particles and the heated walls of the chamber, to control the residence time in the chamber by variation of screw pitch to control air velocity and centripetal forces holding 25 particles against the inner wall of the inner chamber. The use of a central heating tube inside the inner chamber and a screw ensures the maximum surface area for particles to contact the inner chamber wall. 43 Central Heating Tube The Central Heating Tube (11) supports the side of the screw and reduces the area in the middle of the screw thereby increasing both air velocity and centripetal forces. The diameter of the Central Heating Tube (11) can be varied to control air velocity and centripetal force. 5 Heat is also drawn from the manifold into the Central Heating Tube (11) causing the screw to be heated internally. Heat then radiates out from the outside of the Central Heating Tube to the inside of the heated inner chamber (4). After the product is heated by radiated heat the flights of the screw are heated by radiated and conduction heat and then pass this heat by radiation and conduction to the particles and to the 10 inner wall of the inner chamber. This process heat is then feed back through to the pre-heating chamber at the top of the Central Heating Tube (11). Feed Pre-heating Heating air is expensive. It is possible to heat the PR feed prior to introduction to this circuit as at preheating chamber (7), pre-heating tube (6), or before the PR is added to the hopper. The 15 feed is pre-heated from ambient temperature to up to 900 0 C in a heated auger, oven or by others means. Feed preheating improves the overall energy efficiency of the process. Process Parameters - Preheating Pre-heating externally (outside the circuit shown), has the following benefits: * Preheating at temperatures below 800 0 C requires only simple and low-cost plant. Using 20 pre-heated product the plant can process increased volumes of phosphate This reduces the capital cost of the plant and can reduce the amount of lime needed to be mixed with the phosphate needed for very low oxygen atmospheres. * Greater heating efficiencies * Increased plant throughout. 25 EXAMPLE 2 As further illustrated with reference to Figure 4, this process allows for the removal of cadmium at lower temperatures than those used by other processes. 44 Process Description - Main Plant Pre-heating Circuit A pre-heating circuit (in Figure 4) is used to maximise energy efficiency by transferring waste heat into the feed prior to introduction to the main circuit. See process descriptions for pre 5 heater options A & B below. Temperature probes A series of temperature probes (T 1-9) are used to accurately control heat throughout the main circuit. Cooling Augur 10 An inclined augur (19) is used to cool the product. The inclination of the augur causes product to fill the lower end of the augur and prevent air from moving past this point. Particulate Removal After passing through the pre-heating chamber the heated gas flow passes through a particulate filter (at 21) just before feed is introduced. This ensures that contaminants, such as soot from 15 the flame (3), do not reach the RPR. Advantages of the catalytic convertor One or more catalytic converters (or reducers) may be included, located at or in the vicinity of (18). The catalytic converter(s) assist the process because it: * Reduces dangerous carbon monoxide (CO) to safe levels. 20 e Enables a richer flame to be used. * Reduces the oxygen level to almost negligible creating a reducing environment conducive to efficient cadmium removal. Catalytic Convertor An oxidizing catalytic convertor (18) is used on to convert carbon monoxide and oxygen to 25 carbon dioxide. This further reduces oxygen in the airflow enhancing the reducing atmosphere 45 and cadmium removal efficiency. The level of dangerous carbon monoxide is also significantly reduced. The carbon dioxide produced also further add to the inert atmosphere. Stream Acidulation The reactivity of RPR can be increased via acid acidulation. To achieve this, water droplets 5 may be introduced at 22 in the region of the air inlet (2). The water can contain acid - typically phosphoric acid. The stream produced contacts and acidulates the RPR increasing reactivity. Another method that can be used to acidulate the RPR is via using gas plasma to produce nitrous oxides. The feed air may be passed through a gas, plasma and tungsten catalyst (17) located immediately after the burner manifold. At this point the air temperature is already 10 800 0 C. This increases conversion efficiency of nitrogen to nitrous oxides. The nitrous oxides is then converted to nitric and nitrous acid when acidulates the RPR. Yet another method of producing acidic steam is via the nitrous oxides produced by burning fuels. The amount of nitrous oxides produced is relatively low and will only slightly increase the acidity of the steam, but as the steam / water is recycled in the system; acidity will increase 15 to the level required for acidulation to occur. Cadmium is removed by filtration (at point 27). Until this point is reached acid such as nitric acid or phosphoric acid is mixed with the input water and metered in according to the pH level (measured at 28). This method can be used in a stand-alone way to acidify the steam. An oxygen rich flame can be used to increase nitrous oxides formation. The oxidising catalyst 20 then removes additional oxygen achieving a lower oxygen atmosphere. Higher levels of nitrous oxides can be achieved by the use of high nitrogen fuels such as coal and heavy oil. Plasma Heating Torch Another method of producing NO for conversion to acidified steam in the system is by using a 25 plasma heating torch in place of the LPG gas burner. The plasma heating both heats the air and produces NO. Note: The plasma can be introduced either at the heating stage or later in the circuit (see plasma spark plugs). 46 Water Droplets Water droplets are introduced (at 22) to the cold air inlet to the burner/firebox (A) or elsewhere in the system either as cold water or heated steam. The water droplets capture the NO produced and convert it to nitrous oxides. The amount of water introduced is as required to 5 achieve the required affect of converting nitrous oxides to acid and achieving better heat transfer with particles and heated surfaces. Steam Steam can be made by spraying water onto the exhaust gas pipes. This has the benefit of also cooling the exhaust gases. This improves energy efficiency. 10 Recycled Air Hot air from cooling systems is introduced back into the circuit at the flame improving gas combustion and increasing flame heat. Energy efficiency is also improved. Oxv2en Measurement Oxygen levels are measured both before and after the oxidising catalyst to measure oxygen 15 conversion efficiency. EXAMPLE 3 Process Description - Preheater Stage - Option A Having regard to Figure 5, the following is a description of a pre-heater / cadmium removal device in accordance with one embodiment of the present invention. Hot air, Phosphate Rock 20 (PR) and volatised cadmium enter the pre-heater stage at (1). The PR (equivalent to feature 24 in Figure 4) drops out in the product cyclone (2), while the hot air and volatised cadmium continue on to the heat-exchanger (5). Ambient temperature air is introduced at (3) and is heated via heat exchange (5) from the main plant hot air. This heated air (6) is then passed to the air inlet of the main plant. The remaining hot air (initially from the main plant) is passed to 25 stage 2 where it is used to pre-heat the PR feed. It is possible to electrically heat (the air after the first pre-heating/cadmium removal stage in order to use cheap of-peak electricity or electricity from wind turbines. 47 PR feed (9) is introduced at the feed hopper (10) and is heated via heat exchange (12). The pre heated product then passes to the main plant (13). The remaining heated air (14) can be used to boil of cadmium from the first cadmium removal stage (4) Cadmium deposits is removed - removal rods with spinners or flush with liquid solution 5 Cadmium will deposit on the walls during this preheating stage as the temperature falls below 900 0 C. An acid washing solution or 1000 0 C air can be used to remove the cadmium deposits resulting in a concentrated cadmium by-product. EXAMPLE 4 Process Description - Preheater Sta2e - Option B 10 Having regard to Figure 6, the following is a description of a pre-heater / cadmium removal device in accordance with another embodiment of the present invention. Hot air, Phosphate Rock (PR) and volatised cadmium enter the pre-heater stage at (1). The PR (equivalent to feature 24 in Figure 4) drops out in the product cyclone (2), while the hot air and volatised cadmium continue on to the pre-heater (5). Ambient temperature PR feed is 15 introduced at the feed hopper (3). The pre-heater (5) can incorporate any of the following: * A slow turning augur * Spinners (4) * A fixed screw (similar to the main plant) 20 Heat is exchanged (6) from the hot process air to the PR feed. The heated product (7) then goes directly to the main plant where it is introduced at temperatures up to 800 0 C. Cold air is introduced at (9) and further heat exchange takes place at (10) from the hot air and volatised cadmium (8). The heated air is then introduced into the main plant via (12). The remaining air containing volatised cadmium (11) then passes into the condenser / scrubber 25 where the cadmium is cooled and removed under vacuum if necessary. An electrical heater (13) (run from the jet turbine) is heat the air at this point. 48 PR Reactivity Using non-reactive phosphate rock is possible after treatment in this plant. EXAMPLE 5 Assisted Granulation 5 As a result of the method and apparatus of the present invention there is provided a source of finely ground phosphate rock with substantially reduced cadmium content and able to be subsequently used for soil fertiliser products. In addition, the soil fertiliser products may be produced in the form of a granulated product. The production of granules/pellets is further assisted by the process of the present invention is reducing the time and energy inputs required 10 to assist with the pelletisation process and/or the drying time of pelletised/granular products produced. The granules are typically adapted to include various components desirable in the conditioning or treatment of soils. High pressure compaction is preferably used as it results in granules with higher crush strengths - although also this is also affected by the components/additives/agents also used in the pellet 15 creation, which affects not only the pellet/granule strength, but also the dispersion properties. Further, the method of the present invention means RPR of lower reactivity may be used because the grinding to increase the particle fineness and the slow heating of the rock phosphate particles during the calcining process, assist the RPR reactivity. This has the potentially realisable advantage of being able to purchase and use lower reactive RPR at a 20 cheaper cost. Another advantage of the invention is also related to the ability to use lower grade RPR. Fine grinding of RPR also enables more effective removal of cadmium from reactive phosphate rock, providing an additional potentially realisable benefit having regard to reducing negative environmental impacts of using fertilisers including RPR having a high cadmium content. 25 EXAMPLE 6 The following description now relates to further aspects of the plant design as illustrated in Figure 13. In this embodiment typical oxygen reduction is achieved by the use of two reducing catalysts. The efficiency of oxygen removal is achieved by the oxygen level being controlled 49 and maintained at a required low level by means of two reducing catalysts (catalytic converters) in series (illustrated as 18a and 18b). Figure 7 shows typical oxygen reduction achieved by the two reducing catalysts using the calcining apparatus exampled in Figure 13; and also shows the mean percentage oxygen reduction is 62.3%. 5 Located in the circuit prior to the catalytic converters 18a and 18 b, the embodiment of Figure 13 also includes a spark arrester (23). Oxygen Level Measurement Oxygen levels measured before and after both of the reducing catalysts (02 1-3), along with the oxygen level measured periodically at the plant outlet to check for any air leaks in the plant 10 after the reducing catalysts, confirms that a low-oxygen (reducing) atmosphere is present throughout the main plant. Results in Figure 8 show various results where the value of low percentage oxygen values is reciprocated by achieving higher percentage cadmium removal, using the calcining apparatus of the present invention. A greater percentage cadmium removal is achieved from treated PR 15 when the percentage oxygen levels are low. Plant Vacuum This embodiment of the present invention operates under vacuum (29). This is achieved by, for example, an electrically driven suction unit (29). However, other means for enabling a vacuum may be used with the invention. This enables more efficient removal of cadmium. Typically, a 20 1 to 20" water gauge is used. Temperature Measurement Temperature is measured at six different points in the plant circuit (T1 -6). Figure 9 and Figure 12 illustrate the effect of temperature (in 'C) on the percentage of cadmium removed from calcined RPR during operation of the calcining apparatus. The higher 25 the temperature, the greater the percentage of cadmium removal is achieved. The optimum temperature for cadmium removal is around 900 0 C. Residence Times When the feed is preheated this has the effect of increasing the speed of heating and therefore residence time can be reduced to achieve the same cadmium removal effect. 50 Airflow Control Control taps are not used as in previous embodiments, because the plant is operated under vacuum, as shown in the embodiment of Figure 13. Airflow through the plant is controlled by speed drives on an electrically driven suction unit 5 (29) and the regulator on associated gas tanks (2a). Heating Chamber Screw In the embodiment of Figure 13, the screw (15) has a reduced pitch and an increased internal diameter which results in greater particle velocity and prevents material "hanging" in the internal heating chamber (4). 10 Particle Size A 45 micron feed has shown better cadmium removal efficiency and less reduction in reactivity compared with a 75 micron feed. This could be due to the greater heat transfer through the particles below the sintering temperature. Figure 10 shows the percentage of cadmium removed, while Figure 11 shows the effect on 15 reactivity of calcined PR based on finely ground and un-ground PR. Air Cyclones For product removal the plant uses one large 150mm diameter cyclone (12) and two 74mm diameter cyclones in parallel (12a). Collection System 20 Product is initially collected by air cyclones (12 and 12a). Any particles passing the air cyclones are captured in a vertical wet scrubber (13a). Process air is not cooled before the scrubber to prevent the volatised cadmium from recombining with the RPR due to the lower temperature. Feed Loading 25 The plant vacuum system makes it much easier to achieve consistent product (8) feed rates. Should the plant be operated under pressure it is to be noted that air flow is to be managed alongside the feed auger (9) to avoid giving inaccurate feed rates. 51 It should be appreciated the provided description and examples, cover only some of the various embodiments of the present invention. The apparatus and the method of the present invention means RPR of lower reactivity may be used because the grinding to increase the particle fineness and the slow heating of the rock 5 phosphate particles during the calcining process, assist the RPR reactivity. This has the potentially realisable advantage of being able to purchase and use lower reactive RPR at a cheaper cost. Another advantage of the invention is also related to the ability to use lower grade RPR. Fine grinding of RPR also enables more effective removal of cadmium from reactive phosphate 10 rock, providing an additional potentially realisable benefit having regard to reducing negative environmental impacts of using fertilisers including RPR having a high cadmium content. When referring to the description of the present invention, it should also be understood that the term "comprise" where used herein is not to be considered to be used in a limiting sense. Accordingly, 'comprise' does not represent nor define an exclusive set of items, but includes 15 the possibility of other components and items being added to the list. This specification is also based on the understanding of the inventor regarding the prior art. The prior art description should not be regarded as being an authoritative disclosure of the true state of the prior art but rather as referring to considerations in and brought to the mind and attention of the inventor when developing this invention. 20 Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof, as defined in the appended claims. 52

Claims (35)

1. Calcining apparatus for use with a rock treatment process, said calcining apparatus including a chamber for receiving a source of rock to be treated, and said calcining apparatus also including means to introduce the rock material into the chamber; said chamber being adapted to receive a heated gaseous flow; said flow being heated via means to achieve a predetermined temperature required to treat the rock; and said calcining apparatus including centrifugal means and collection means and said calcining apparatus characterised by using rock material pre-ground to particles of less than 500 micron.

2. Calcining apparatus for use with a rock treatment process as claimed in Claim 1 wherein the treatment process is undertaken in an oxygen reduced atmosphere.

3. Calcining apparatus for use with a rock treatment process as claimed in Claim 2 wherein the treatment process is undertaken under vacuum.

4. Calcining apparatus for use with a rock treatment process as claimed in Claim 2 wherein the treatment process is undertaken under pressure.

5. Calcining apparatus for use with a rock treatment process as claimed in Claim 3 or 4 wherein the rock is pre-ground to particles less than 150 micron in size.

6. Calcining apparatus for use with a rock treatment process as claimed in Claim 5 wherein, the rock is pre-ground to particles typically less than and 75 microns.

7. Calcining apparatus for use with a rock treatment process as claimed in Claim 6 wherein the rock is pre-ground to particles typically less than 45 microns.

8. Calcining apparatus for use with a rock treatment process as claimed in Claim 7 wherein up to at least 95% of the rock is pre-ground to particle sizes between minus 500 micron to minus 20 microns.

9. Calcining apparatus for use with a rock treatment process as claimed in Claim 8 wherein the pre-ground rock particles are heated by a gaseous flow including air and wherein the oxygen in said air comprises less than 2%.

10. Calcining apparatus for use with a rock treatment process as claimed in Claim 9 wherein the heated gaseous flow is achieved by heated air and at least one or a combination of: a) A flammable gas. b) A flammable material. c) Steam. 53 d) Electric heating means located around any one or more of the outer chamber, the inner chamber circumference and within or around the central internal conduit/tube located within the inner chamber.

11. Calcining apparatus for use with a rock treatment process as claimed in Claim 10 wherein the heated gaseous flow is required to reach a predetermined treatment temperature of between 600'Celsius and 1000 Celsius required to vapourise materials from the rock being treated by heating of the rock particles during treatment of the rock particles within the chamber.

13. Calcining apparatus for use with a rock treatment process as claimed in Claim 12 wherein the chamber includes an outer heated chamber and inner heated treatment chamber/cavity.

14. Calcining apparatus for use with a rock treatment process as claimed in Claim 13 wherein the outer heated chamber receives the heated gaseous flow and directs said flow to pre-heat the pre-ground rock particles prior to entry to the inner heated treatment chamber/cavity.

15. Calcining apparatus for use with a rock treatment process as claimed in Claim 14 wherein the inner heated treatment chamber/cavity receives the heated gaseous flow via a central conduit/tube to indirectly heat the finely ground rock particles within the inner heated treatment chamber.

16. Calcining apparatus for use with a rock treatment process as claimed in Claim 15 wherein the inner chamber receives the finely ground rock particles such that the particles begin to fall due to the effects of gravity until they contact the heated gaseous flow and are carried by that flow within the inner chamber.

17. Calcining apparatus for use with a rock treatment process as claimed in Claim 16 wherein the inner heated treatment chamber/cavity is configured to retain the rock particles therein for a residence time sufficient to treat the rock particles and effect vaporisation of materials therefrom.

18. Calcining apparatus for use with a rock treatment process as claimed in Claim 17 wherein the inner heated treatment chamber/cavity is configured to increase the residence time of the rock particles via any one, or a combination of: a) Sections of increasing and decreasing internal diameters of the chamber configured to affect the rate of flow of the heated gaseous flow through the 54 chamber, such that the wider and narrower internal sections result in expansion and restriction of the airflow, respectively. b) A tangentially directed upward heated gaseous flow. c) Deflector means/vanes, or similarly configured projections, projecting into the interior of the inner chamber to deflect the particles thereby retaining the particles within the heated gaseous flow. d) Spinners within the inner chamber to direct the movement of the heated gaseous flow and maintain the swirling action of the particles of rock.

19. Calcining apparatus for use with a rock treatment process as claimed in Claim 18 wherein the increased residence time of the rock particles in the inner chamber effects over time, vapourised material removed from the particles and treated rock particles.

20. Calcining apparatus for use with a rock treatment process as claimed in Claim 19 wherein the vapourised material within the heated gaseous flow and treated rock particles are directed to at least one centrifugal or cyclone means.

21. Calcining apparatus for use with a rock treatment process as claimed in Claim 20 wherein the at least one centrifugal means separates the treated particles from the vapourised material and any ultrafine rock particles carried therewith are fed back into the calcination process.

22. Calcining apparatus for use with a rock treatment process as claimed in Claim 21 wherein the vapourised material is separated out of the heated gaseous flow using high intensity scrubbing means and/or condensation means and thereafter disposed of.

23. Calcining apparatus for use with a rock treatment process as claimed in Claim 21 wherein the treated particles are directed into collecting means.

24. Calcining apparatus for use with a rock treatment process as claimed in Claim 23 wherein the collecting means effects the treated rock particles in a form available to be used as a soil treatment.

25. Calcining apparatus for use with a rock treatment process as claimed in Claim 24 wherein the treated rock particles for use as a soil treatment are cooled to 90 degrees Celsius then pelletised.

26. Calcining apparatus for use with a rock treatment process as claimed in Claim 25 wherein the treated rock particles for use as a soil treatment are particles of either or both Reactive Phosphate Rock (RPR) or Phosphate Rock (PR). 55

27. Calcining apparatus for use with a rock treatment process as claimed in Claim 26 wherein the treated rock particles of either or both Reactive Phosphate Rock (RPR) or Phosphate Rock (PR) for use as a soil treatment are treated to reduce the cadmium content therein.

28. Calcining apparatus for use with a rock treatment process as claimed in Claim 27 wherein the treated rock particles of either or both Reactive Phosphate Rock (RPR) or Phosphate Rock (PR) for use as a soil treatment are treated to reduce the cadmium content therein by incorporating limestone (CaCo 3 ) into the phosphate rock feedstock introduced for calcination and wherein calcined lime is also a desirable fertiliser.

29. Calcining apparatus for use with a rock treatment process as claimed in Claim 28 wherein the treated rock particles of Reactive Phosphate Rock (RPR) for use as a soil treatment are treated to reduce the cadmium content therein while retaining or improving any reactivity of the Reactive Phosphate Rock (RPR) treated.

30. A method of calcining rock via a rock treatment process using calcining apparatus, said calcining apparatus including a chamber for receiving a source of rock to be treated, and said calcining apparatus also including means to introduce the rock material into the chamber; said chamber being adapted to receive a heated gaseous flow; said flow being heated via means to achieve a predetermined temperature required to treat the rock; and said calcining apparatus including centrifugal means and collection means and said calcining apparatus characterised by using rock material pre-ground to particles of less than 500 micron.

31. A soil treatment composition produced by calcining apparatus, said calcining apparatus including a chamber for receiving a source of rock to be treated, and said calcining apparatus also including means to introduce the rock material into the chamber; said chamber being adapted to receive a heated gaseous flow; said flow being heated via means to achieve a predetermined temperature required to treat the rock; and said calcining apparatus including centrifugal means and collection means and said calcining apparatus characterised by using rock material pre-ground to particles of less than 500 micron.

32. Fertiliser granules produced via calcining apparatus for use with a rock treatment process, said calcining apparatus including: a chamber for receiving a source of rock to be treated, and said calcining apparatus also including means to introduce the rock material into the chamber; said chamber being adapted to receive a heated gaseous 56 flow; said flow being heated via means to achieve a predetermined temperature required to treat the rock; and said calcining apparatus including centrifugal means and collection means and said calcining apparatus characterised by using rock material pre-ground to particles of less than 500 micron.

33. Calcining apparatus as claimed in any one of Claims 1-29 herein described with reference to the included examples and attached figures.

34. A method of calcining rock via a rock treatment process using calcining apparatus as claimed in Claim 30 herein described with reference to the included examples and attached figures.

35. A soil treatment produced by calcining apparatus as claimed Claim 31 herein described with reference to the included examples and attached figures.

36. Fertiliser granules as claimed in Claim 32 herein described with reference to the included examples and attached figures. 57