AU2002301717B2

AU2002301717B2 - Dolomite Based Quick Release Organic Broad Acre Fertiliser

Info

Publication number: AU2002301717B2
Application number: AU2002301717A
Authority: AU
Inventors: Connor James Horley
Original assignee: Calix Pty Ltd
Current assignee: Calix Pty Ltd
Priority date: 2002-10-01
Filing date: 2002-10-01
Publication date: 2011-02-10
Anticipated expiration: 2022-10-01
Also published as: AU2002301717A1

Description

AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: DOLOMITE BASED QUICK RELEASE ORGANIC BROAD ACRE FERTILISER The following statement is a full description of this invention, including the best method of performing it known to me: Field of the Invention s This invention relates to the manufacture of a quick release organic fertiliser, from the ore called Dolomite. Backpround In the mid 1980's Dolomite was identified by a man named Count Dolomous, who detailed a Dolomite as the dual Carbonate of Calcium and Magnesium containing 53% 10 Calcium Carbonate (CaCO 3 ), 45% Magnesium Carbonate (MgCO 3 ), 2% impurities such as Silica, Ferries and Alumina. Dolomite was in fact the first refractory, early steel makers relied upon Dolomite bricks for the lining of kilns and fire zones, Since that time, it has become the habit to call any rock, having Calcium Carbonate is (CaCO 3 ), and Magnesium Carbonate (MgCO 3 ), as its major constituents Dolomite. For the purpose of this invention, the term Dolomite refers to the modem interpretation of the name, In the 1900's American and European agricultural industries relied heavily upon Dolomite as a fertiliser. Huge deposits of Dolomite were mined in many countries so that 20 a finely ground Dolomite could be used as a soil sweetener and organic fertiliser. 3162988 1:LNBl -2 Dolomite was mined in coarse rock sizes between 4" and 15" and placed in vertical open hearth kilns and cooked for many hours using coal or wood as fuel. The 12 to 24 hour cooking process was a hit or miss process and Calcined only the Magnesium 5 contained in the outer skin of the Dolomite rocks. This was because the Magnesium Carbonate (MgCO3) contained within the rock had a Calcining temperature of approximately 750'C whereas the Calcium Carbonate (CaCO3) contained in the outer skin of the Dolomite rocks had a Calcining temperature 10 of approximately 1100'C. When the Dolomite rocks were removed from the kilns and crushed the resultant powdered Dolomite contained various quantities of lightly Calcined Magnesium in the form of Caustic Magnesia Oxide (MgO?CO3) sometimes called Activated Dolomite. 15 Millions of tons of the powered Activated Dolomite were used In Tennessee America between 1950 and 1980 12,000,000 tons of Activated Dolomite were shipped from one flotation operation. Activated Dolomite was applied to pastures and crops such as Tobacco to correct Magnesium deficiency in the form of low 20 soluble Activated Dolomite Fines, as a quick release Fertiliser. Current production of Activated Dolomite Fertiliser is severely restricted because of the costs of fuel labour and other circumstances. 25 Shortly before and after World War 2 Chemical Phosphate Fertilisers were introduced. The price of oil and other fuels used to Calcine Dolomite became excessive and partially Calcined Activated Dolomite Fertiliser production became almost extinct.

3 The world agricultural industry now faces the fact that the over use of chemical fertilisers has rendered huge tracts of the world's available agricultural land virtually unusable because of acid and salt contamination. A problem which is removed by the application of activated Dolomite fines to soils. s There is previous knowledge that super heated steam has a catalytic effect upon Magnesium Carbonate entrained within Dolomite (W.H. McIntyre and TB. Stansel (1930)). Summary of the Invention It is the primary object of this invention to introduce a method of calcining the to Magnesium Carbonate (MgCO 3 ) entrained within Dolomite fines enabling the production of an activated Dolomite in a rapid and inexpensive manner. As described herein, Dolomite ore when ground to under 100 mictrons and subjected to an atmosphere of super heated steam at controlled pressure, quantity, temperature and velocity will release

CO

2 from the Magnesium Carbonate (MgCO3) contained within the 15 powdered Dolomite within 6 and 60 seconds at temperatures as low as 450'C and in certain embodiments within 3 and 60 seconds. The present invention father relies upon the creation of the said super heated steam conditions in a vertical kiln so that the Magnesium Carbonate (MgCO 3 ) contained within the powdered Dolomite will when pre heated and dropped through the controlled super 20 heated steam atmosphere within the vertical kiln become partially calcined to any selected degree during the controlled drop time through the kiln, A further object of this invention is that by adjusting temperature, quantity, pressure and velocity of the super heated steam the degree of calcination of the entrained Magnesium Carbonate (MgCO 3 ) within the powdered Dolomite will be carried at will. 3162988 1:LNB 4 A further object of this invention is to control the calcining conditions within the super heated steam so that the Calcium Carbonate (CaCO 3 ) entramned within the Dolomite does not calcine at all. The current technology available to the calcining industry makes the partial or selective 5 calcination of the Magnesium Carbonate (MgCO 3 ) contained in Dolomite without calcining the contained Calcium (CaCO3) virtually impossible This is because current calcining technology makes use of dry heat or exhaust gas heat as the heating mediums, The use of this type of kiln makes the recovery of released Carbon Dioxide (CO2) 10 impossible with resultant huge quantities of Carbon Dioxide (CO2) being released to the atmosphere in the exhaust gasses. One aspect of the present invention is a method to calcine Dolomite fines of the types mentioned to allow the total recovery of released Carbon Dioxide (CO2). For example one tonne of Magnesium Carbonate (MgCO 3 ) contains over 500 kg of 15 Carbon Dioxide (C0 2 ) which becomes a future environmental hazard if niot controlled collected and used as by products. Detailed Description As described herein, selected and graded quantities of the pre crushed and ground Dolomite ores are fed into the throat of a vertical kiln at a controlled speed and quantity. 20 The kiln may be manufactured from any suitable material including but not limited to stainless steel, brick, refractory brick, refractory castables and other materials capable of maintaining structural stability at calcining temperatures (see Photograph 1). The height of the kiln can be varied to allow for selected fall or drop times from the top to the bottom 3162988 1:LNa 5 of the kiln for ores having differing particle sizes or impurity. The cross sectional area of the kiln may be varied to allow a larger or smaller free fall area. The installation of mechanical vibrating tilting or rotating baffles in the interior of the kiln may be required for some types of calcination results, which may require extended or s shortened drop times through the kiln. The exterior surface of the kiln walls shall be insulated by air gap and refractory coating (see Photograph 2). Super heated steam having a pre determined temperature, pressure, quantity and velocity will be injected into the kiln through steam jets located at various selected positions 10 through the height of the kiln and within the body of the kiln. The selected pre sized powdered Dolomite ores are fed into the pre heating hopper situated at the top of the vertical kiln. When the ore has attained the required pre heating temperature of between 450*C and 500*C, it is fed into the kiln through the controlled atmosphere of super heated steam. 15 The catalytic affect of super heated steam upon Magnesium Carbonate (MgCO 3 ) contained in the dolomite particles brings about an immediate release of CO 2 from the Magnesium Carbonate. Selected sizes of Dolomite fees, the drop time through the kiln, selected super heated steam temperature, pressure, quantity and velocity will vary the CO 2 release time between 20 6 seconds and 60 seconds, or in certain embodiments between 3 seconds and 60 seconds. The amount of CO 2 removed will be adjusted by varying the steam pressure, quantity, temperature, pre heat temperature and actual fall or exposure time to the super heated steam and importantly the particle size of the ore feed. 3162988 I:LNB 6 A further advantage of this invention is that the super heated steam fed into the kiln will become entrained with the CO 2 released which will allow for C02 to be removed for by product manufacture and the steam recycled through the super heater and the kiln to save operating and fuel costs. 5 This invention further relates to the fact that any type of fuel may be used to generate the steam and super heated steam. This invention further relates to the fact that Dolomite rocks are selectively fully or partially calcined at a greatly reduced temperature and time frame in an atmosphere of controlled super heated steam. 10 1 refer to actual tests carried out using a test super heated steam calcining kiln manufactured to my design which consisted of a 20 meter high 250 mm diameter stainless steel tube as the kiln (see Photograph 1). The calcining tube was encapsulated in refractory insulating panels on all sides (see Photograph 2). is The gap between the stainless steel tube and the insulation panels was kept at 450 0 C by using 10 gas jets operating through vents cast into the panels. Superheated steam at a temperature of 475 0 C at a pressure of 10 kilopascals was supplied inside the stainless steel kiln by 10 steam jets at various positions through the height of the kiln pipe. 20 A 5 kg charge of Dolomite having an analyses of: 54% Calcium Carbonate (CaCO 3 ) 3162988 I:LNB -7 40% Magnesium Carbonate (MgCO3) 6% impurities A particle size of 60 microns. was fed by hand into a pre heating hopper on the top of the 5 kiln (see photograph 3) the hopper was equipped with a fast release feed flap. After pre heating to 450'C the entire charge of Dolomite was dropped en mass through a one millimetre feed dispersing baffle situated at the top of the kiln throat. 10 The mesh spread the charge over the entire area of the kiln tube which allowed the feed to be evenly affected by super heated steam as it dropped within the kiln tube. The drop time was recorded as 6 seconds. The throat of the kiln was cleared of any remaining dolomite by 15 the dropping of 5kg of steel half millimetre sized balls through the kiln 10 seconds after the dolomite charge had been released from the pre heat feed hopper. The steel balls were sieved from the now Calcined Dolomite the dolomite weighed on scales accurate to one tenth of one gram. 20 The weight of the C02 in the Magnesium Carbonate (MgCo3) contained within the powdered Dolomite before Calcining was estimated by known factors at 1040 grams. After the 6 second drop through the calciner the dolomite had reduced in weight by 936 grams indicating 90% loss of the 25 contained C02 in the Magnesium after exposure to the super heated steam for 6 seconds. This indicated the catalytic effect of super heated steam on the Magnesium Carbonate (MgCo3) contained in finely ground Dolomite Carbonate Rock.

-8 Tests conducted on the Calcined Dolomite indicated no release of the C02 contained in the Calcium Carbonate (Caco3) side of the Dolomite charge. Many differing tests were conducted on many types of Dolomite 5 ores from many countries in various grain or feed sizes on all occasions the degree of Calcination could be varied and controlled by the parameters hereinto referred.

Claims

1. A fertilizer suitable for use on Crops or pastures comprising at least partially calcined carbonate rock, wherein the carbonate rock is at least partially calcined at a 5 temperature of between 450*C and 600 0 C for 3 to 60 seconds in an atmosphere comprising super heated steam.

2. The fertilizer of claim 1, wherein the carbonate rock is a powder with a particle size of between 10 to 200 microns,

3. The fertilizer of claim I or claim 2, wherein said carbonate rock is at least 10 partially calcined in a vertical kiln.

4. The fertilizer of any one of claims 1 to 3, wherein the super heated steam is provided at a pressure of between 5 kilopascals to 100 kilopascals.

5, The fertilizer of any one of claims I to 4, wherein the carbonate rock is dolomite. 15

6. A method of producing at least partially calcined carbonate rock, the method comprising passing powdered carbonate rock through a vertical kiln for a period of between 3 to 60 seconds, wherein as it passes through the vertical kiln the powdered carbonate rock is exposed to a temperature of between 450'C and 600"C and an atmosphere which comprises superheated steam so that the MgCO 3 component of the 20 carbonate rock is at least partially calcined.

7. The method of claim 6, wherein the powdered carbonate rock has a particle size of between 10 to 200 microns.

8. The method of claim 6 or claim 7, wherein the super heated steam is provided to the kiln atmosphere at a pressure of between 5 kilopascals to 100 kilopascals. 25

9. The method of any one of claims 6 to 8, wherein carbon dioxide produced during the calcining is collected,

10. The method of any one of claims 6 to 9, wherein the carbonate rock is dolomite.

11. At least partially calcined carbonate rock, produced by the method of any one of claims 6 to 9. 30

12. A device for at least partially calcining carbonate rock, comprising a vertical kiln comprising a top end, an interior cavity and a bottom end, wherein feedstock of carbonate rock is loaded into the top end of the vertical kiln, travels through the interior cavity of the vertical kiln and exits from the bottom end of the vertical kiln, wherein said feedstock is exposed to the interior cavity of the kiln for between 3 to 60 seconds, 35 the interior cavity of said vertical kiln being heatable to a temperature of between 450'C and 600'C, and wherein the device is adapted to deliver super heated steam to the interior cavity of the vertical kiln.

3025797-1 - 1

13. The device of claim 12, wherein the vertical kiln comprises a core tube Positioned in the interior cavity of the vertical kiln for the recovery Of carbon dioxide generated during calcining,

14. The device of claim 12 or claim 13, wherein the interior cavity of the vertical kiln comprises baffles which are adapted to increase the exposure time of feedstock of carbonate rock within the interior cavity of the vertical kiln.

15. The device of any one of claims 12 to 14, wherein the device is adapted to deliver super heated steam to the interior cavity of the kiln at a rate of between I L/sec to 50 L/sec. 10

16. The device of any one of claims 12 to 15, wherein the length of the interior cavity of the vertical kiln is at least 20 m. 22 December 2010 Calix Limited 15 Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON 3025797-1