AU2012101890B4 - A method for zoning a site for blasting purposes - Google Patents

Abstract

A method for zoning a site for blasting purposes, the method including the steps of testing of samples at various test locations within the site at at least one temperature below 55'C for reactivity and creating a zoned map of the site with at least one zone therein based on the temperature of each test location within the site.

Description

A METHOD FOR ZONING A SITE FOR BLASTING PURPOSES Field of the Invention. 10011 The present invention relates to generally to the field of explosive blasting and in particular to zoning of a site for blasting purposes. Background Art. [0021 The use of explosives to break rock is an intrinsically hazardous process. These hazards have been studied over the years and modem mining methods have evolved to minimise the inherent risks of blasting under most conditions. [0031 In certain situations, unwanted reactions between an explosive and a rock being blasted may result in premature detonations with potentially fatal results. The reactions can be caused by rock chemistry, temperature or a combination of both. [0041 Typical nitrates used in the mining industry (including but not limited to) are ammonium nitrate, calcium nitrate and sodium nitrate. The reaction of nitrates with sulphide containing minerals is an auto-catalysed process that can, after some induction time, lead to a runaway exothermic decomposition even if the starting temperature of the mixture is at an ambient temperature. [0051 Reactive ground is defined in the Australian Explosives Industry and Safety Group (AEISG) Code of Practice as "rock that undergoes a spontaneous exothermic reaction after it comes into contact with nitrates. The reaction of concern involves the chemical oxidation of sulphides (usually of iron or copper) by nitrates and the liberation of potentially large amounts of heat. The process is unpredictable and can be so violent that it results in mass explosions." [0061 If ground that is to be blasted is classified as "reactive ground" then there are restrictions on the type of explosives that can be used and also restrictions on the period of time that an explosive charge can remain in the blasting hole before detonation (known as the "sleep" time). [0071 There are two separate steps that need to be considered when discussing testing procedures in relation to reactive ground: 2 e Reactivity Screening - this test method is used to identify whether ground samples are reactive with ammonium nitrate. " Product Selection Testing - this test method is used to confirm whether an explosive product is suitable for a specific reactive application. [0081 Two laboratory screening tests may be used in determining the reactivity of ground samples and in determining the suitability of explosive products to be used within the ground namely the isothermal reactive ground test and the temperature ramping test. [009] The Isothermal Reactive Ground Test has been developed for use in screening reactive samples and for carrying out sleep time analysis. "Standard" test conditions cover blasting in normal temperature ground (ie <55*C). However if the risk assessment indicates that a higher temperature may be experienced then this temperature should be adopted as the standard. [00101 A summary of the test method is as follows with the detailed test procedures given in Appendix 2 of the AEISG Code of Practice: * Rock samples are crushed to a fine powder. " The rock powder is then mixed with chemically pure ammonium nitrate and a solution to simulate the by-products of sulphide rock weathering. " The mixture is heated to and kept at 55*C (for non elevated temperature ground sites) the adopted standard temperature and monitored for exothermic reactions. For elevated temperature ground sites, the test is carried out at the maximum recorded in-hole temperature based on temperature logging and historical data, or at the maximum nominated temperature limit at the site. " Unless a reaction is observed first, the test is run at least up to the nominated sleep time (or longer when testing inhibited explosives). If exceptionally long sleep times are required in specialised blasting applications, it may be more appropriate to use a Temperature Ramping Test (see Section 8.2.2 Australian Explosives Industry and Safety Group Code). e The mixture is monitored for any visual reactions (such as colour change or signs of chemical reactions such as gas liberation) and reactivity is identified by a change in temperature, detected using thermocouples with continuous temperature logging.

3 e This test method is capable of picking up exotherms greater than 2*C above the background temperature. Samples that exhibit an exotherm greater than 2*C are classified as reactive and require further investigation. " Samples that exhibit a greater rate of increase while ramping up to the test temperature need to be investigated further. [0011] The above testing regime clearly indicates that the Code of Practice interprets all samples that are reactive at 55*C are deemed to be reactive at all temperatures below 55*C. In other words, the Code of Practice does not provide for testing to ascertain reactivity at any temperature below 55 0 C. [00121 The AEISG Code of Practice does allow for delineation of zones on a blasting site. The Code of Practice states that delineation of a site into reactive and non-reactive ground shall only occur after significant research into the nature and extent of reactivity has been carried out. In some cases it may not be possible to delineate and the entire site should be classified as reactive. [00131 Delineation requires close cooperation between those with geotechnical expertise and explosive providers based on reactive ground sampling and testing. [00141 Delineation of a site should not occur if there are no clear indicators as to what ground is reactive and what is not. Delineation may be possible if there are: * Clear zones of geological type. " Clear zones based on sulphide levels. " Drill cuttings are geologically logged for the presence of sulphides and a procedure is in place for utilising this information to determine what product is to be loaded into the reactive and non reactive holes. " Temperature profiles across the site. [00151 If delineation is established across a site appropriate buffer zones between reactive and non-reactive areas must be established and rigorously managed. Procedures for the loading of explosives into the two areas needs to be developed, and must include a detailed emergency action plan should the wrong product be loaded into the wrong area.

4 [00161 It is therefore clear from the above that the testing of ground for the purposes of classifying the ground as "reactive ground" or not as provided by the AESIG Code of Practice is conducted at a temperature of 55*C. If the ground is reactive at 55*C, then it is deemed to be reactive at all temperatures below that as well regardless of whether the ground is actually susceptible to uncontrolled exothermic decomposition at a lower temperature or not. [00171 The AEISG Code of Practice does not preclude zoning based on temperature differences between different portions of the one site but the AEISG Code of Practice limits zoning to be allowable at temperatures greater than 55*C. [00181 It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country. Summary of the Invention. [00191 The present invention is directed to a method for zoning reactive ground for blasting purposes, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice. [00201 With the foregoing in view, the present invention in one form, resides broadly in a method for zoning a site for blasting purposes, the method including the steps of: testing of samples at various test locations within the site at at least one temperature below 55*C for reactivity; and creating a zoned map of the site with at least one zone therein based on the temperature of each test location within the site. [00211 The method of the present invention will preferably find use in relation to a site that has been zoned as "reactive ground" according to the conventional testing regime at 55*C or for any site in which blasting may occur in order to provide a better indication of whether the site contains areas that are actually reactive ground rather than simply having been deemed reactive ground according to the conventional testing regime conducted at 55*C. [00221 Typically the samples will be samples of ground or rock which may be from a particular site or of a particular type.

5 [00231 The method therefore will preferably be directed to zoning a site with at least one area with a ground temperature of less than 55*C. 100241 The method will preferably include the further step of establishing a safe sleep time period for a non-inhibited explosive at each test location based on the temperature at the test location. Preferably, the site may be divided into one or more zones based on temperature or more preferably, a maximum sleep time allowed for an explosive charge in at least one zone based on temperature in that zone and/or based on the rock or ground type (reactivity). 10025] Preferably, the testing according to the method of the present invention will be undertaken at a variety of temperatures below 55'C to the actual rock temperature in order to develop a plurality of reactivity profiles relating one or more temperatures to any other variable including rock or ground type, maximum sleep time, time to reaction or any other zoning parameter that may be useful. One or more of these profiles can then be used to zone a site accordingly. [00261 Once the reactivity profiles have been created, the zoning of a site can be accomplished relatively easily by testing the ground temperature and delineating a zone according to the ground temperature. This also means that the zoning of the site can take place as desired and is not restricted to zoning prior to commencing blasting. The zoning can be updated at any time, simply by re-testing the ground temperature. [0027] The temperature/reactivity testing will preferably be performed according to at least one of the methods provided in the AEISG Code of Practice. [00281 In particular, the temperature/reactivity testing will preferably be according to either the Isothermal Reactive Ground Test or Temperature Ramping Test as described in the AEISG Code of Practice with the exception that the testing takes place at one or more testing temperatures below 55*C rather than at 55*C only. [00291 The sleep time testing may use the AEISG Code of Practice testing methodology and equipment as well as: 1. A number of standard samples made up of inert material that is prepared for testing in exactly the same manner as the reactive ground samples. These standard samples can be 6 used as control samples so it is easy to determine if a temperature variation is an artefact of the test which is critical in sleep time testing. 2. A number of sub-samples are used (usually 3 but can be more), preferably from the same sample to deal with and attempt to negate the presence of reactive variability in sub samples. The test is aimed at testing the most reactive of the most reactive sample from the test results from the 55'C testing. The sub-samples are preferably approximately 18g so it is easy to see why there can be variability between subsamples. [00301 The method of zoning ground of the present invention will preferably enable the use of non-inhibited explosives if the ground is not reactive at a temperature of less than 55'C rather than the present situation in which if the ground is found to be reactive at 55'C then the ground is deemed reactive at all temperatures below 55*C and inhibited explosives are used, irrespective of whether the ground temperature is below 55*C and therefore may not actually be reactive. [00311 This will typically allow the division of a site into a plurality of zones each with a corresponding maximum sleep time calculated based on the time to reaction of an explosive charge at the temperature of the ground in that zone as established from the temperature/reactivity testing. [00321 The method also allows use of less inhibited or mildly inhibited explosives at ambient in-hole temperature as a less preferred option. In this case, the testing shows that the rock type is still reactive at ambient hole temperatures but it is far less reactive than at 55'C hence a less inhibited explosive can be used. So if normally an explosive with 40wt% or higher emulsion percentage is required to inhibit then a lower content emulsion explosive can be used which is less expensive due to less emulsion and less expensive as is lower density as well. The example is likely to be BSOC where the rock may still be reactive at ambient temperature but a less inhibited explosive can be used. This can result in significant savings - in this case $2 million pa instead of $3 million pa using ANFO. [00331 Typically, this requires establishing an ambient ground temperature over the site and more particularly how the ambient ground temperature changes over the site. A temperature profile of the site is preferably created. [00341 The step of testing the reactive ground temperature profile at a plurality of test locations in the site will typically involve a number of locations. It is inefficient to test too many 7 test locations and a representative sample will not be gathered if too few test locations are tested. Therefore, as a preliminary step to testing the reactive ground temperature profile, the method may include the step of dividing the site into a number of preliminary zones including a minimum of two test location in each zone based on a risk analysis and then amending or adjusting the preliminary zones into the zones of the zoned map after the AN reactivity versus temperature testing has been completed across the ambient rock temperature zones at the site. Typically, the site will be divided into a plurality of two or more areas in the preliminary step and each area will include a minimum of two or more test locations based on the size of the area. 100351 If during the temperature testing a small area shows a great variation in temperature, then additional testing holes may be used more increased accuracy. The opposite may also be the case. 100361 Preferably, the method of the present invention includes performing tests of the ground temperature in the blast holes and/or the exploration holes in the site. 100371 The ground temperature in the plurality of test locations will typically used to establish a temperature profile or map of the site. This map can then be divided into zones. Alternatively, any parameter relating to reactivity of an explosive and measured at each of the plurality of test locations can be used to establish a zoned profile or map of the site. [00381 The zones may have any size but typically, if the scale of the zone is too small, then it may be extremely difficult in practice to identify the zones using the map. Therefore, a predetermined minimum area for each zone may be provided as a part of the zoning method. The zones do not have to be equal in area. [00391 Alternatively, the zone map which is output from the method may include position data relating to the limits of each of the zones in the site. The zoned map may be output such that the information relating to any zone is capable of representation or identification using a display device which is equipped or associated with a positioning mechanisms such as GPS positioning. In this way, the zone map may be output as a data file which is then capable of representation on a display device with accompanying positioning data in order that the user can easily locate the limits of each of the zones within the site. [00401 As well as initial profiling of the site (that is, preferably prior to blasting), there will preferably be ongoing testing over time as well, in order to monitor for any changes in the ground 8 temperature and/or reactivity which may lead to a change in zoning. It is may also be that where possible, the temperature in each of the test locations be monitored more or less continuously and that a zoned map is capable of generation at any point in time based on either historical information, the latest test information or more preferably, real-time test data. [0041] The ground temperature testing may be achieved by any method with the preferred method being that which is as accurate as possible. [0042] The temperature testing will typically occur by logging the temperature at a representative number of locations within the site in order to identify the ground temperature in each of these locations. [00431 According to a preferred method, the temperature will also be monitored in the exploration holes prior to mining beginning, so that preliminary zoning can occur prior to mining as well. [0044] A buffer or redundancy factor may be used in the zoning step. For example, the zoning may take place according to the actual temperature in a particular test location or alternatively, the zoning may take place according to the actual temperature in a test location plus a buffer. [0045] A buffer of approximately 5*C is preferred but the buffer may be increased or decreased depending upon the precision with which the zoning is to take place. Generally speaking, the larger the buffer, the more redundancy is built in and the more certain a user can be when placing the blasting charges. Typically, the buffer is added to the actual temperature measured in order to achieve a calculated temperature. The zoning can take place according to the actual or calculated temperature. It is particularly preferred that the buffer is built into the display of the zones perhaps as simply as representing a zone as being one step more reactive on the zoning map than it actually is according to the temperature/reactivity profile in order to increase the safety factor. [0046] The method of the present invention includes the step of creating a zone map of the site which preferably includes output of a visual representation with the zones indicated on a site map. [0047] Any type of map may be generated. Any scale may be used.

9 [00481 The output may be capable of adjustment such that the size of the zones can be adjusted to prevent a zone being defined of below a certain size. [00491 The zoning will preferably take place according to the temperature information gathered in the testing phase and with reference to a temperature versus reactivity profile or temperature versus sleep time profile. These profiles may be created by undertaking a variety of tests in order to create the profiles. The profiles can then be used with reference to the actual or calculated temperature in the test locations to provide an indication of reactivity based on the temperature, and zoning on that basis. [00501 Preferably, the zoning is based on the temperature but may be indicated in the zone map as either temperature, reactivity or maximum sleep time. [00511 The process is typically one in which the ground temperature is tested, and this ground temperature is compared to a temperature versus reactivity profile or a temperature versus time to reaction profile in order to establish a maximum sleep time in that test location which is then represented on an output as a zone. As mentioned previously, the more test locations, the greater the precision with which the zones can be defined but there will be an optimum number of test locations for each site. [00521 The method of the present invention may also include using a factor of safety for testing. For example, the factor of safety can be used in order to calculate the test time at a particular temperature based on a maximum allowable sleep time in practice. One example of this would be that if the maximum allowable sleep time in practice for an explosive charge at a particular test location is two days, then the period of testing at the same temperature to ensure the veracity of the maximum sleep time of 2 days, at a factor of safety of 4, will be eight days. [00531 In an alternative form, the present invention in one form, resides broadly in a computer implemented method for zoning a site for blasting purposes, the method including the steps of: testing of samples at various test locations within the site at at least one temperature below 55*C for reactivity; and 10 creating and outputting a zoned map of the site with at least one zone therein based on the temperature of each test location within the site in computer or human readable format. [0054] Preferably the method of the present invention will be provided in a computer implemented form and in a particularly preferred form, will be embodied in computer software which is stored in a memory and processed by a processor in order to put the invention into effect. [0055] The software will typically be provided with an input section such that any one or more input parameters relating to a site such as temperature or other information such as ground type or explosive type may be entered. The software will then typically use one or more databases, preferably provided with the software, to zone the site according to the method. Once the zoning has been achieved, a visual representation of the site identifying the zones will typically be output. 10056] The one or more databases will typically include information relating to the reactivity profiles that can then be used by the software to zone the site according to the input parameters. Normally, the input parameters will include at least temperature and rock or ground type at a predetermined number of locations within the site. An appropriate sampling technique is provided in the AEISG Code of Practice. [0057] The output of the zoning is preferably an information set which is capable of display on a display device. The information set will include digital information relating to the site itself and a corresponding zone descriptor for each of a plurality of test locations within the site. A display means such as a personal computing or display device will then preferably take the output information set and display the information in a visual form with corresponding positioning data identifying the limits of each zone in the site. A variety of electronic devices available are capable of providing a visual display with positioning data including smart phones or other mobile computing devices. [0058] The manner in which the calculated values are output is important in order to allow the calculated values in the output to be easily understood by a user without technical experience interpretation of some or all of the calculated values.

11 [0059] The output may be in any computer or human readable form. One preferred form of output is a data file including the parameters calculated according to the method. [00601 A more preferred form is the generation and output of a "map" representing any one or more of temperature and/or maximum allowable sleep time. It is particularly preferred that the map be a graphical representation of the temperature or more preferably, maximum allowable sleep time or a more basic "safe/not safe" indication (such as for example, coloured red for not safe and green for safe). [00611 A map typically is a visual representation of an area, a symbolic depiction highlighting relationships between elements of that space such as objects, regions, and themes. In the context of the present invention, the "map" will preferably represent the zones of the site based on temperature or more preferably, maximum allowable sleep time or reactivity. [00621 The map may be static, two-dimensional, geometrically accurate (or approximately accurate) representations of three-dimensional space, dynamic or interactive, even three dimensional. The map may depict geography or topography, and may represent any space, real or imagined, without regard to context or scale. [00631 "Contour" lines may be used to define the zones according to the nature of the variable being mapped. In the present case, the variable will typically be ambient ground temperature or more preferably, maximum allowable sleep time or reactivity in a particular zone based on the ground temperature and taking into account the ground composition or type. [00641 The "contour" lines (often just called a "contour") will preferably define zones of equal temperature or, maximum allowable sleep time or reactivity. The map is preferably a map illustrated with contour lines. The map is preferably provided with precise location information in relation to the location of the limits of each zone. [00651 The map may include topographical elements such as valleys and hills, and the steepness of slopes as well as structures. The contour interval of the map is preferably the difference in factor of safety between successive contour lines. [00661 When the contour lines are close together the magnitude of the gradient is large: the variation is steep. A level set is a generalization of a contour line for functions of any number of variables.

12 100671 Contour lines are typically curved. The configuration of these contours allows map readers to infer relative gradient of a parameter and estimate that parameter at specific locations. Contour lines may be either traced on a visible three-dimensional model of the surface, or interpolated from temperature or more preferably, maximum allowable sleep time, as when a computer program threads contours through a network of observation points of area centroids. In the latter case, the method of interpolation affects the reliability of individual isolines and their portrayal of temperature or more preferably, maximum allowable sleep time. [00681 Other visual representation methods may be used including colour variation for different zones according to the spectrum with the red end of the colour spectrum indicating zones of high temperature or low sleep time and the violet end of the colour spectrum indicating zones of low temperature or high sleep time. These coloured zones may be overlaid on a standard map representation with landmarks or other marker points. [00691 Generation and output of one or more visual representations of the results of the calculated values will preferably be an additional step in the method and system of the present invention. [0070] The method of the present invention may include the step of co-generation of a legend indicating the parameters used to zone the site with the generation of the map output. The legend may appear on the map output or may be separate to the map output but will typically provide the user with a means to understand and decode the map output. [00711 The method of the present invention may require preparation of a map of the site in a digital format in order that an output map with the zones can be created which represents the zones accurately relative to the site. This preparation may include digitising a map of the site including landmarks and/or features of the site. The digitised map of the site will preferably be input and stored in one or more databases used according to the method. [00721 In still another form, the invention resides in a visual indication generation apparatus for generating a visual output of a site including a plurality of zones including an input interface for input of a measure of reactivity of ground samples at various test locations within the site at at least one temperature below 55'C, a processor to collate the measures of reactivity at the test locations relative to a map of the site and an output mechanism for outputting a zoned map of the site with at least one zone therein based on the temperature of each test location within the site in computer or human readable format.

13 [00731 The apparatus may include any of the features of the methods disclosed herein in the identification of collation of measures of reactivity to output the zoned map. [00741 The output may be as simple as a matrix consisting of explosive type, temperature and sleep time that can then be used to select the appropriate explosive for that blast at that temperature and the required sleep time. When provided in this form, the output is likely to be more useable in certain situations, particular to the charge shot loaders. [00751 The present invention is also well adapted for use in a vertical orientation as well as a horizontal orientation. In these cases, the map output may include a zoned cross section. This will especially occur in underground mines or environments as temperature increases with depth. [00761 Combinations of zoning horizontally and zoning vertically could also be used to give a multi-dimensional profile. [00771 Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention. Brief Description of the Drawings. [00781 Various embodiments of the invention will be described with reference to the following drawings, in which: [00791 Figure 1 is a schematic view of one possible example output from the method of the present invention in the form of a site topographical map with ground temperature zones indicated thereon. [00801 Figure 2 is a schematic view of a second possible example output from the method of the present invention in the form of a site map with ground temperature zones indicated thereon in a an alternative format with the zones delineated thereon. [00811 Figure 3 is simple view of a possible output matrix relating explosive type, ground reactivity, ground temperature with a maximum sleep time according to a preferred embodiment of the present invention. Detailed Description of the Preferred Embodiments 14 100821 According to a particularly preferred embodiment of the present invention a method and system for zoning a site for blasting purposes is provided. [00831 According to the preferred embodiment, a background testing regime of a variety of rock/ground types should be undertaken at a variety of temperatures and in light of any other relevant testing parameters in order to establish a set of profiles relating the parameters to one another and in particular, relating temperature to each of the parameters and to reactivity. Once these profiles have been obtained by testing, the profiles can then be used to quickly zone a site based on the temperature (and rock/ground type) that particular test locations in site. [00841 A test example for the background testing to create a temperature versus reactivity profile is as follows: Test Example [00851 The preparation of the samples is based on the AEISG method, with the samples crushed in a jaw crusher to <6 mm, and milled to a fine powder in a pulverising mill for 45 seconds. Immediately after this is finished, the sample is sieved to separate the <250 im fraction. This fraction is then vacuum sealed and frozen to inhibit oxidation of the sample. [00861 The test method used is also based on the AEISG method, and consists of testing the samples to determine if a reaction could occur when ammonium nitrate is loaded in the ground. Equal parts of the sample (18 g) and ammonium nitrate (18 g), together with a ferric sulphate/ferrous sulphate solution (4 g), and placing into an aluminium block that is set to a predefined temperature, an attempt is made to force a reaction from the sample. Should the temperature of the sample deviate by more than 2.0'C from a blank sample, the sample is deemed reactive at the set temperature. There is no clear correlation between the reactivity of a sample at 55*C and lower temperatures, so it is necessary to test at multiple temperatures below 55*C in order to properly characterise the relationship between temperature and reactivity for a given sample. [00871 In addition to this, the length of time between the start of the test and any reaction occurring increases as temperatures fall. As a consequence of this, a critical feature of the test procedure for temperatures below 55*C is that the samples must be tested for longer when at a lower temperature. This is in order to allow the reaction products which act as catalysts to build up within the sample. The test protocol as proposed calls for testing to be performed for a 15 minimum of 12 days at 45*C, and 20 days at 35*C, which is designed to translate into a suitable safety factor in the mining/quarrying and construction environments. [0088] Test data is logged at 10 - 30 second intervals, with the sample temperature being recorded, and compared to a blank sample (18 g of sand mixed with 18g of ammonium nitrate plus 4 g of weathering agents) present within the same block as the test sample. If a deviation of greater than 2.0*C from the baseline is recorded, then a reaction is deemed to have occurred within the sample. The time to the onset of the exotherm, and the strength of the exotherm is recorded. [0089] The following data indicates the need for multiple temperature testing. All samples were reactive at 55*C, and non-reactive at 35'C, reactivity at 45'C is variable. This is the case for all the measures listed below. If reactivity at 55*C was a reliable indicator for low temperature reactivity RG231 would be expected to be more reactive than RG282, and of similar reactivity to RG269, but this is clearly not the case. Sample ID Test temp / Exotherm Onset time Onset temp Mass Reactive? *C / *C / HH:MM / *C Loss /% RG207 55 9.6 07:40 55 10.1 Y 7814 45 3.0 N 35 4.5 N RG231 55 45 01:02 55 21.3 Y 7838 45 4.7 N 35 4.3 N RG246 55 2.4 00:28 53 1.5 Y 7853 45 2.2 00:58 45.5 2.3 Y 35 3.3 N RG254 55 24 11:35 56 19.1 Y 7861 45 1.5 N 35 3.0 N RG269 55 40.5 00:55 53 24.8 Y 7876 45 23.8 00:50 45 6.3 Y 35 4.1 22.00 36 7.0 Y RG282 55 44 02:49 57 38.1 Y 16 7889 45 4.2 05:30 46.8 3.5 Y 35 6.3 N [00901 This test data clearly shows how the sleep time for an explosive charge of the time to reaction generally increases as the temperature drops. The sleep time generally increases by a factor of 2 for each 1 0*C drop to much larger than this as the Activation Temperature is reached. For example, it can be seen that that for Sample ID 7876, the time to reaction is approximately 50 minutes at 45*C (which is approximately the same as at 45*C, but increases to 22 hours at 35*C. This is a change by a factor of 26. 100911 The temperature can then be tested at each of a number of test locations within a site at blasting holes and exploration holes and once this information is available, the site can be zoned accordingly using the reactivity profiles generated from the background testing. [00921 The method of the present invention may require preparation of a map of the site in a digital format in order that an output map with the zones can be created which represents the zones accurately relative to the site. This preparation may include digitising a map of the site including landmarks and/or features of the site. 100931 The output of the zoning is preferably an information set which is capable of display on a display device. The information set will include digital information relating to the site itself and a corresponding zone descriptor for each of a plurality of test locations within the site. A display means such as a personal computing or display device will then preferably take the output information set and display the information in a visual form with corresponding positioning data identifying the limit of each zone in the site. [00941 The output may be in the form of a topographical map such as is illustrated in Figure 1 with a corresponding temperature profile represented by different colours representing different ground temperature and therefore, different reactivity. Certain colours will indicate non-reactive ground and others reactive ground at different temperatures. [00951 The output may be as simple as a matrix consisting of explosive type, temperature and sleep time that is used to select the appropriate explosive for that blast at that temperature and the required sleep time.

17 100961 Figure 2 is an illustration of a less precise map not including topographical information. [00971 Figure 3 is an illustration of a possible output matrix that is produced after testing of ground samples at various test locations within the site at a variety of temperatures below 55*C for reactivity. The output matrix relates explosive type, ground reactivity, temperature and sleep time to select an appropriate explosive for a particular blast location within the site, at a given temperature and a required sleep time. This type of output would be useful to provide to charge shot loaders for example. [00981 In the present specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers. [00991 Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

Claims (5)

1. A method for zoning a site for blasting purposes, the method including the steps of testing of ground samples at various test locations within the site at at least one temperature below 55*C for reactivity and creating a zoned map of the site with at least one zone therein based at least in part on the temperature of each test location within the site.

2. A method for zoning a site for blasting purposes as claimed in claim 1 including a further step of establishing a safe sleep time period for a non-inhibited explosive at each test location based on the temperature at the test location.

3. A method for zoning a site for blasting purposes as claimed in either one of the preceding claims wherein the site is divided into one or more zones based a maximum sleep time allowed for an explosive charge in at least one zone.

4. A computer implemented method for zoning a site for blasting purposes, the method including the steps of: testing of samples at various test locations within the site at at least one temperature below 55*C for reactivity; and creating and outputting a zoned map of the site with at least one zone therein based on the temperature of each test location within the site in computer or human readable format.

5. A visual indication generation apparatus for generating a visual output of a site including a plurality of zones including an input interface for input of a measure of reactivity of ground samples at various test locations within the site at at least one temperature below 55*C, a processor to collate the measures of reactivity at the test locations relative to a map of the site and an output mechanism for outputting a zoned map of the site with at least one zone therein based on the temperature of each test location within the site in computer or human readable format.