AU785302B2 - Waterways lime spreader - Google Patents

Description

P/00/011 Regulation 3.2 COMMONWEALTH OF AUSTRALIA Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: WATERWAYS LIME SPREADER The following statement is a full description of this invention, including the best method of performing it known to us: 2 This invention relates to a waterways lime spreader, which is an apparatus for treating waterways, watercourses and disturbed soils affected by the runoff from acid sulphate soils, and for general pH correction.

The Commonwealth, and State and local governments, and agri-business in Australia have become aware of decreasing water quality existing on the coastal strip of South-East Queensland and northern New South Wales. The problem on this coastal strip has been identified by academic study as acid sulphate runoff from urban development, agricultural development or natural developments.

As described by Mitch Tulau in a paper entitled "Management of Acid Sulphate Soils in New South Wales Policy, Organisation, and Regulation" in The Australasian Journal of Natural Resources Law and Policy, Vol. 6, No. 1, 1999, acid sulphate soils (ASS) are sediments deposited under estuarine conditions, that is, close to sea level, which sediments contain the sulphidic mineral pyrite (iron disulphide, FeS 2 In Australia, the ASS of most concern are those formed within S 15 the past 10,000 years, after the last major sea level rise. When the sea level rose and inundated land, sulphate in the seawater mixed with land sediments containing iron oxides and organic matter. The resulting chemical reaction :0 .produced large quantities of iron sulphides. It is estimated that there are two million hectares of acid sulphate soils in Australia containing approximately one oio billion tonnes of iron sulphides.

tl0 0000 *o0 As long as acid sulphate soils are not disturbed or drained, they are relatively harmless and are termed 'potential ASS (PASS)', because the pyrites are **°contained within a layer of waterlogged soil. However, if the sediments are exposed to air, the pyrite is oxidised, and sulphuric acid is generated. One tonne 25 of iron sulphide can produce about 1.5 tonnes of sulphuric acid. As a result of the generation of sulphuric acid, soil acidity (pH) may fall to below 4, at which level elements such as iron, arsenic and aluminium become soluble in toxic quantities, and their precipitates affect water quality. Runoff from acid sulphate soils into watercourses and waterways can have disastrous consequences: massive kills of aquatic life can occur due to low pH and aluminium toxicity. Chronic effects on aquatic systems are common and widespread and include habitat degradation, 3 altered waterplant communities, weed invasions by acid-tolerant plants, secondary water quality changes, the presence of disease, reduced aquatic food resources, reduced migration potential of fish, and reduced recruitment, survival and growth rates across a wide range of aquatic species.

ASS areas are generally degraded backswamp wetlands. Acid sulphate soils in such areas have historically been activated by drainage of potential ASS areas for conversion to agricultural land. Clearance in 1972 of 700ha of mangrove swamp within sight of the city of Cairns in North Queensland, resulted, by 1999, in the daily release of the equivalent of a "small swimming pool" of sulphuric acid into the ocean.

More recently, disturbance of acid sulphate soils is more likely to result from development of ASS areas for residential, commercial and entertainment use.

Many of the coastal areas of New South Wales and Queensland which are subject to the pressures of development are ASS areas: 60,000 hectares of ASS have been identified in south-east Queensland alone. The Commonwealth Government, State and Local governments in Queensland and New South Wales, °Oil• and agri-business, have become aware of decreasing water quality on the Gold Coast/Tweed coastal strip, which has been identified by academic study as being caused by acid sulphate runoff resulting from urban development, agricultural 20 development and natural development. The runoff is a major pollution problem, as described earlier in this specification, causing serious fish kills as was seen in the aftermath of the Lismore and Grafton floods in early 2001.

The policy of the Queensland Government is to minimise the disturbance of acid sulphate soils, and to manage the effects of any disturbance such that the longterm economic and environmental impacts are minimised. As acid sulphate soil S:runoff is already occurring in locations such as Queensland's Gold Coast, and in northern New South Wales, and as development of ASS areas in at leats those States will continue, an effective and economical system, for ameliorating the effects of such runoff on waterways and watercourses, is required.

4 It is an object of this invention to provide an improved apparatus for doing waterways and watercourses.

The invention provides a waterways lime spreader for treating a waterway, watercourse or disturbed soils, which have been affected by runoff from acid sulphate soils, with crushed, abraded or ground calcium limestone rock to correct the pH level of said waterway, watercourse or disturbed soils, characterized in that said waterways lime spreader includes a hopper adapted to contain limestone rock, a rotatable drum adapted to tumble said limestone rock to crush, abrade or grind said limestone rock to produce particles having a predetermined size, and a conveyor adapted to transport limestone rock from said hopper to said drum, said drum having one annular end wall, through the opening in which limestone rock is adapted to be delivered by said container to the interior of said drum, and in that means are provided in said annular end wall to permit only those particles below said predetermined size to exit said drum for dosing of said a waterway, watercourse or disturbed soils.

An embodiment of the invention will be described in detail hereinafter with S. reference to the accompanying drawings, in which: oo. Fig. 1 is a side elevation of one embodiment of a waterways lime spreader "'"according to the present invention; Fig. 2 is an end elevation of the waterways lime spreader of Fig. 1; Fig. 3 is a partial cross-section of the waterways lime spreader of Figs. 1 and 2; and ego* Fig. 4 is a partial cross-section through a rotating drum which forms part of the waterways lime spreader of Figs. 1,2 and 3.

The waterways lime spreader of the present invention has been designed to provide accurate dosing of calcium limestone into bodies of water or watercourses as a means of controlling acid sulphate runoff from surrounding land, thereby raising pH levels to an acceptable level. The calcium limestone is in the form of rocks, usually of a size in the range 10 Omm to 150mm, which are crushed and/or ground by the waterways lime spreader to provide calcium limestone for the aforementioned dosing.

The waterways lime spreader of Figs. 1 and 2 includes a drum 12 which is of no fixed dimension in width or diameter, although 500mm in width and one metre in diameter has proven to be very effective and efficient. The size of the drum 12 is basically governed by magnitude of application and is therefore relative.

The drum 12 may be manufactured from mild steel, stainless steel, aluminium or extruded plastic. A prototype waterways lime spreader 10 was fabricated from 4mm mild steel plate.

The drum 12 has an unobstructed opening 14 made possible by the use of an external necklace-type bearing 14 (Fig. made from mild steel and incorporating rollers (not shown) made from PTFE or high density rubber with needle roller bearings (also not shown).

The drum 12 has a fixed axle 16 at the other end of drum 12 from opening 14 which axle 16 is supported by a main support bearing (not shown), and which is driven by a drive motor 18. The motor 18 is a 0.746kW (one horsepower) with 20 variable speed and a 68:1 reduction. The rotational direction is clockwise and revolutions per minute are variable from 12 to 33. At 15rpm, production is 10% of drum 12 capacity, and at 33rpm, it is 30% of drum 12 capacity. Production rates °coo are also governed by the scale of hardness of the product.

The ends 20 of the drum 12 are slotted with tapered diffuser slots 22 or with i 25 varying size diffuser holes 24 (Fig. small at the extremities and increasing in size towards the centre. The diffuser slots/holes 22/24 are positioned 50 apart, around the drum 12, as shown by reference numeral 50 in Fig. 4. The extremities of the diffuser holes 24 are positioned approximately 100mm from the outer edge of the wall 20 of drum 12, as indicated by reference numeral 52 in Fig. 4. This distance is critical in that that part of drum 12 contains all uncrushed material 6 above 20 microns, allowing only very fine particles of crushed material to be washed and diffused through the slots/holes 22/24 into the sump 26 or water surrounding the waterways lime spreader. Reference numeral 54 indicates the distance between the slots/holes 22/24 and the inner edge of wall 20 of drum 12.

The inside of drum 12 has attached an abrasive lining 28 (Fig. 4) consisting of abrasive low-wearing plates of suitable material. The prototype waterways lime spreader successfully used 6mm mild steel checkerplate with very little indicated wear. Other suitable abrasive plate materials are bisalloy, carborundum, hardfacing material or any wear material suitable for product to be crushed/abraded/ground.

The method of filling and maintaining the working level of material in the rotating drum 12 is by using a rubberised rock conveyor 30 built into a storage hopper 32.

The flow control of material into the rotating drum 12 is achieved by using a torque load sensor (not shown) on the main drive motor 18, sequencing as follows:- Low torque demand sensed; Rock conveyor 30 motor 34 activated; Material shifted from holding box (hopper 32) to rotating drum 12; Drive motor 18 sensor senses increased torque loading; and :Pre-set torque level achieved and rock conveyor 32 switched off.

V 20 This process repeats itself until the rock hopper 32 is empty. When the drive motor 18 sensor senses low torque for longer than two minutes, the waterways lime spreader 10 is completely switched off, indicating that the hopper 32 is empty.

The waterways lime spreader 10 also has a sump 36 designed to fit around the lower half of the rotating drum 12. The sump 36 consists of three key component, the sump per se, a product extractor venturi 38, and a sludge and by-product •goimpurities screen 40, which is removable.

The role of the sump 36 is to collect water loaded with finely ground product. The product extractor venturi 38 uses bypass water from the main pump 42 to 'suck' water laden with diffused particles and discharges it directly to the surrounding 7 water. Any sludge and by-product impurities are collected in the bottom of the sump 36 and may be removed by removal of the screen 40, and cleaning.

The holding box or hopper 32 is a standard box constructed from 3mm mild steel plate. The prototype waterways lime spreader 10 had a hopper 32 with a one cubic metre capacity, with 300 tapering sides converging down onto the chain and rubber belt conveyor 30, which is powered by a .09325kW (Ya horsepower) motor 42 with a 60:1 reduction gearbox (not shown). The conveyor motor 42 is activated by the torque sensor referred to earlier in this specification. The motor 42 and gearbox provides 8rpm.

The specific role of the water pump 42 is to pump water into the rotating drum 12 at a rate of 2275 litres per hour (500 gallons per hour), creating a positive flow of ground product into the sump 36 via the diffuser ports 22, 24. The pump 42 has a capacity of 11,375 litres per hour (2,500 gallons per hour). The excess water is diverted via a variable diverter valve (not shown) and water inlet 44 to power the venturi 38, which in turn sucks the sump 36 clean.

The waterways lime spreader 10 has been specifically designed to be environmentally friendly, having very low power requirements. Only approximately "1.3055 kW (1.75 horsepower) is required to carry out the full process. Suitable 20 power supplies include solar-wind/battery storage, mains power, LPG/intemal 20 combustion engine, solar hydrogen/internal combustion engine, and solar hydrogen/bi-polar membrane.

The waterways lime spreader of the present invention is designed to be fitted to any number of transport systems to facilitate access to all sites. Such transport systems include floating the waterways lime spreader on pontoons, attaching the waterways lime spreader to a three-point linkage for tractor use, and locating it on S* a trailer-truck arrangement.

It can be seen that the waterways lime spreader of the present invention provides an improved apparatus for safe and accurate dosing of waterways and watercourses with crushed calcium limestone.

Claims (9)

1. 3. Apparatus according to claim 2, characterized in that at least part of the interior of said substantially cylindrical drum is provided with an abrasive surface.
2. 4. Apparatus according to claim 3, characterized in that said abrasive surface 000. is constituted by plates.
3. 5. Apparatus according to any preceding claim, characterized in that said predetermined size is 20 microns or less.
4. 6. Apparatus according to any preceding claim, characterized in that drum is adapted to be rotated by a first motor.
5. 7. Apparatus according to any preceding claim, characterized in that said conveyor is adapted to be driven by a second motor.
6. 8. Apparatus according to claim 7, characterized in that a torque load sensor associated with said first motor is responsive to the change in torque thereof resulting from the change in amount of limestone rock in said drum, the speed of said conveyor being controlled by said torque load sensor to control the amount of limestone rock in said drum.
7. 9. Apparatus according to any preceding claim, further characterized by a water pump adapted to supply water to said drum. Apparatus according to any preceding claim, further characterized by a sump located around the lower portion of said drum, said sump being adapted to collect water containing particles having said predetermined size, which particles have exited said drum through said slots or holes. S11. Apparatus according to claim 10, further characterized by a product extractor venturi, which is also supplied with water by said water pump, said *product extractor venturi being adapted to suck said water containing particles having said predetermined size from said sump for discharge to said waterway, watercourse or disturbed soils. •:o S 25 12. Apparatus according to any one of claim 10 or claim 11, further characterized by a sludge and by-products impurities screen, said screen being removable for cleaning. oooo
8. 13. Apparatus according to claim 4, characterized in that said plates are constructed from bisalloy, carborundum or hardfacing material.
9. 14. Apparatus according to claim 6, characterized in that said first motor is adapted to operate at rotational speeds between 12rpm and 33rpm. A waterways lime spreader for treating a waterway, watercourse or disturbed soils, substantially as herein described with reference to the accompanying drawings. DATED this 9 July 2006 JOHN CHRISTIANSEN Patent Attorney for the Applicants: JASON IAN NATHANIEL BEATH JAMES GILDER DIXON