CA1287746C - Production method of combined phosphorus fertilizer and soil conditioner - Google Patents
Production method of combined phosphorus fertilizer and soil conditionerInfo
- Publication number
- CA1287746C CA1287746C CA000520584A CA520584A CA1287746C CA 1287746 C CA1287746 C CA 1287746C CA 000520584 A CA000520584 A CA 000520584A CA 520584 A CA520584 A CA 520584A CA 1287746 C CA1287746 C CA 1287746C
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- Canada
- Prior art keywords
- phosphorus
- phosphate rock
- citric acid
- water
- rock
- Prior art date
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Abstract
ABSTRACT
A method for producing combined phosphorus fertilizer and soil conditioner in which phosphate rock and, as reaction matter, organic acidic matter are used. In a method according to the invention, the acidic mass is organic, for instance, bark waste, peat, waste fibre from a pulp or paper mill, sawdust or similar matter.
A method for producing combined phosphorus fertilizer and soil conditioner in which phosphate rock and, as reaction matter, organic acidic matter are used. In a method according to the invention, the acidic mass is organic, for instance, bark waste, peat, waste fibre from a pulp or paper mill, sawdust or similar matter.
Description
7~
~RODUCTION METHOD OF COMBI~!ED PHOSPHORUS FERTILIZER AND SOIL
NDITIONER
The phosphorus in phosphate rock or in its concentrates ;s insoluble or only slightly soluble in water and thus avatlable for plants in limited quantities. In producing phosphorus fertilizers, the objective is to increase the solubillty of phosphorus. Normally the solubility of phosphorus contained in the fertilizer is defined as a proportion of the soluble phosphorus, soluble either in water, in ammonium citrate or in 2 % citric acid, compared to the total phosphorus content. The most common production method of phosphorus fertilizers is to treat phosphate rock with an inorganic acid, producing a compound suitable for fertilizing purposes as such, or for further processing.
Another method for producing phosphorus fertilizers is the heat treatment of a mixture of phosphate rock and some other substances at a high temperature.
Phosphorus fertilizers are also obtained from iron ores containing phosphorus, as a by-product in the steel industry.
The phosphorus fertilizers are produced by a reaction of phosphate rock with an inorganic acid, according to the methods known today:
When sulphuric acid is used for the reaction with phosphate rock, the reaction product is a mixture of monocalcium phosphate and calcium sulphate (gypsum), called superphosphate.
(Ca3(PO4)2)3 CaF2 + 7H2S04 ~
Phosphate rock Sulphuric acid (Fluorine apatite) 3Ca(H2PO4)2 + 7CaSn4 + 2HF~I~
monocalcium calcium hydrogen phosphate sulphate fluoride The superphosphate contains approximately 8% phosphorus, of which at least 93% is soluble in water.
7~7~ c~
When the -tricalcium phosphate in phosphate rock is allowed to eact with sulphuric acid and water, the reaction products are phosphoric ac;d and calcium sulphate:
Ca3(PO4)2 + H2SO~ + 6H20~ 3CaS04.2H20 -~
2H3PC~I, Phosphoric acid is used in a -further reaction to produce phosphorus fertilizers, such as triple superphosphate and ammonium phosphates.
In a reaction of phosphate rock with phosphoric acid, triple superphosphate, an almost pure monocalcium phosphate compound, is produced:
ffl'~ P~
(Ca3(P04)2)3 CaF2 ~ 14H3P04-~~1OCa~:tt~F~, '' + 2HF~
The phosphorus content o-f the triple superphos~hate is approximately 22%, of which at least 93% is soluble in water.
The reaction product of phosphate rock and hydrochloric acid is dicalcium phosphate (CaHP04), which has little value as a fertilizer. The reaction o-f phosphate rock with nitric acid produces a mixture of monocalcium phosphate and calcium nitrate.
A-fter calcium nitrate has heen removed, the mixture contains monocalcium and dicalcium phosphates. The ~I:P ratio in the fertilizer is generally in the range of 1:0.44...1:1.3, and its content of soluble phosphorus is 0...80%, depending on -the production method.
Phosphorus fertilizers manufactured by heat processes include Rhenania phosphate, produced hy heating a mixture of phosphate rock, sodium carbonate and arenaceous quartz at a temperature of 1200C.
~ 3'7~
--`alO(P04)6F2 + 3Na2C03 ~ 25iO2 + ~120 6CaNaP04 + 2CaSiO~ + 3C02 -~ 2~F
Rhenania phosphate Rhenania phosphate has a phosphorus content of 11% and is soluble in basic ammonium citrate.
Iron ore containing phosphorus yields Thomas slag as a hy-product in the steel industry. Limestone and oxygen are adde~ to the molten iron ore, thus separating the slag on the sur-face of the mixture.
Thomas slag contains approximately 7...10% phosphorus, of which 90~ is soluble in a 2% solution of citric acid.
The process of treating phosphate rock with sulphuric acid is very complex and requires a high pressure, great accuracy and a great deal of energy. Another reaction product is toxic hydrogen fluoride. Sulphuric acid is not only toxic but also expensive, due to the complexity of its production process and the high input of energy required. Although superphosphate contains calcium sulphate, an excessive amount of calcium sulphate waste is also produced in the process, thus causing an environmental hazard.
When treating phosphate rock with sulphuric acid and water in order to produce phosphoric acid, the hazards are the same as mentioned ahove, with the exception that even more calcium sulphate waste is produced. In addition, the valuable micro nutrients and lanthanides are lost in the process.
Phosphoric acid can be regarded as a mere intermediate product, because its use as a fertilizer is very inconvenient.
Consequently, it is further processed into other fertilizers, such as triple superphosphate, as described above, or fertilizing compounds.
S
~_ 26350-7 The reactions oE phosphate rock with hydrochloric or nitric acid are uti:lized very ln~requently.
During heat treatment o-E phosphate rock, the substances contained in the rock are retained in the -Eertilizer. However, the required temperature of 1,200C is extremely high, involving very high energy consumption. In addition, the phosphorus in the end produc-~ i5 not water-soluble.
Thomas slag is one of the oldest phosphorus EertilizersO
It is, however, produced only by the steel industry, and only if the iron ore contains phosphorus. Another disadvantage of the process is that it causes considerable noxious odours.
The invention eliminates or considerably reduces -the previously mentioned hazards as follows:
- Consumption of energy remains remarkably low.
- No industrially produced inorganic acids are needed.
- There are no environmental hazards in the process, such as toxic reaction products, odour or waste products.
- The nutrient elements of phosphate rock are almost com-pletely retained in the fertilizer.
The present invention provides a method for producing a combined phosphorus fertilizer and soil conditioner which process comprises:
(a) heating an organic material selected Erom the group consisting of uncomposted bark waste, peat, waste pulp fibres and sawdust having a pH of less than 6 and a moisture content of at least 40% by weight to a tesnperature in the range of 40C to 120C
to produce an acidiEied, moist organic massi 7~4~
-4a~- 26350-7 (b) grlndlng p'hosphate rock to rl part:icLe s:i~e oE rlbOut 0.02 to 3m1n and, i:E the solubility of phosphorus in the rock in 2 citric acid is less than 10~ of total rock phosphorus, t'hen `heatin~ resulting phosphate rock particles to a temperature in the range of 50C to 800C, to produce phosphate rock particLes; and (c) admixing and reacting said moist organic mass with said phosphate rock particles to yield said fertilizer.
An Application of the method is described in detail below, with reference to the adjoining drawing which shows a schematic outline of an embodiment of -the method of the invention.
The organic material, consisting of uncomposted bark waste or pea-t, is fed from a feed silo, pos. 1, to the grinding unit, pos. 2. If waste fibre from a pulp or paper mill or sawdust is used in addition to or instead of t'he ma-terials men-tioned above, the organic ma-terial can be fed to the process directly from the tank, pos. 3. Waste fibre is understood as precipita-ted slurry from a water treatment station of a pulp or paper mill and thus contains mainly short wood fibres not suitabLe for pulp or paper production. This slu:rry always contains very fine particles of bark.
All the materials mentioned must be acidic, with a pH of less than 6, prefera'bly lower than 5.5. The reaction mass of bark, peat, cellulose was-te material or sawdust is`heated in the reac-tor furnace, pos. 4, to a temperature of 40 to 120C, depending on the 7~
- 5 ~ 26350--7 water content o~ the mass; t'he greater the w~ter ~ontc-nt, the hig'her the temperature, and the higher the temperature of the pnosphate rock, the Lower the temperature o~ the mass. This process corresponds to the process described in U.S. Patent 4,571,254 entitled "A method for producing fertilizers from wood ashes and softwood bark or from other wood waste ma-terial", with the exception that the water content of the fresh organic material should be 40~ at the minimum. This requirement ls no-t included in the production method described in ~.S. Patent 4,571,254.
After the reactor furnace, pos. 4, phosphate rock, either magmatic, metamorphic or sedimented in origin or a concen-trate of these rocks, is fed into the process. The rock is to ~e preprocessed in the following way: firs-t, the rock is ground in a grinder. pos. 2A, -to a particle size of 0.02 to 3 mm. The smaller -the particle size, the higher the content of phosphorus, soluble in water and/or in citric acid, in the fertilizer. The optimum size is 0.02 to 1 mm. After grinding, the rock is transferred to a rotating heating ~urnace, pos. 4A, in w'hich the surface tempera-ture is approximatel~ 800C. The par-ticles are rapidly heated to a temperature of 50 to 800C, with an optimum temperature of 400 to 500C. The optimum temperature depends on the quality of the phosphate rock and on its water content. The closer to t'he optimal temperature the reaction takes place, the higher the con-tent oE soluble phosphorus in water and/or in citric acid in the end product.
3 ~3 7~L~
If in i-ts natural state -the solubility o:E the phosphorus in the phospha-te rock in citric acid is at least oE 10 ~ (concen-tration of the citric acid 2 %), heating is unnecessary and the phosphate rock at a temperature of about 20~C is mixed with the heated acidic organic mass.
After this stage, the mass of phosphate rock and organic reaction mass from the reactor furnace, pos. 4, are allowed to collide and mix. Generally, the higher the pressure under which the phosphate rock was formed, the higher the temperatures must be, thus also leading to higher pressures at the mixing stage.
This results in partial or complete disintegration of the phosphate rock or its concentrate, due to the following factors:
1. Because the pH of the organic reaction mass is lower than that of the rock, the acidity of the mixture will tend towards a state of equilibrium. The lower the pH of the organic matter is, the stronger the chemical reaction between -the organic matter and the phospha-te rock will be, and the higher the content of phosphorus soluble in water and/or in citric acid in the fertilizer will also be.
~RODUCTION METHOD OF COMBI~!ED PHOSPHORUS FERTILIZER AND SOIL
NDITIONER
The phosphorus in phosphate rock or in its concentrates ;s insoluble or only slightly soluble in water and thus avatlable for plants in limited quantities. In producing phosphorus fertilizers, the objective is to increase the solubillty of phosphorus. Normally the solubility of phosphorus contained in the fertilizer is defined as a proportion of the soluble phosphorus, soluble either in water, in ammonium citrate or in 2 % citric acid, compared to the total phosphorus content. The most common production method of phosphorus fertilizers is to treat phosphate rock with an inorganic acid, producing a compound suitable for fertilizing purposes as such, or for further processing.
Another method for producing phosphorus fertilizers is the heat treatment of a mixture of phosphate rock and some other substances at a high temperature.
Phosphorus fertilizers are also obtained from iron ores containing phosphorus, as a by-product in the steel industry.
The phosphorus fertilizers are produced by a reaction of phosphate rock with an inorganic acid, according to the methods known today:
When sulphuric acid is used for the reaction with phosphate rock, the reaction product is a mixture of monocalcium phosphate and calcium sulphate (gypsum), called superphosphate.
(Ca3(PO4)2)3 CaF2 + 7H2S04 ~
Phosphate rock Sulphuric acid (Fluorine apatite) 3Ca(H2PO4)2 + 7CaSn4 + 2HF~I~
monocalcium calcium hydrogen phosphate sulphate fluoride The superphosphate contains approximately 8% phosphorus, of which at least 93% is soluble in water.
7~7~ c~
When the -tricalcium phosphate in phosphate rock is allowed to eact with sulphuric acid and water, the reaction products are phosphoric ac;d and calcium sulphate:
Ca3(PO4)2 + H2SO~ + 6H20~ 3CaS04.2H20 -~
2H3PC~I, Phosphoric acid is used in a -further reaction to produce phosphorus fertilizers, such as triple superphosphate and ammonium phosphates.
In a reaction of phosphate rock with phosphoric acid, triple superphosphate, an almost pure monocalcium phosphate compound, is produced:
ffl'~ P~
(Ca3(P04)2)3 CaF2 ~ 14H3P04-~~1OCa~:tt~F~, '' + 2HF~
The phosphorus content o-f the triple superphos~hate is approximately 22%, of which at least 93% is soluble in water.
The reaction product of phosphate rock and hydrochloric acid is dicalcium phosphate (CaHP04), which has little value as a fertilizer. The reaction o-f phosphate rock with nitric acid produces a mixture of monocalcium phosphate and calcium nitrate.
A-fter calcium nitrate has heen removed, the mixture contains monocalcium and dicalcium phosphates. The ~I:P ratio in the fertilizer is generally in the range of 1:0.44...1:1.3, and its content of soluble phosphorus is 0...80%, depending on -the production method.
Phosphorus fertilizers manufactured by heat processes include Rhenania phosphate, produced hy heating a mixture of phosphate rock, sodium carbonate and arenaceous quartz at a temperature of 1200C.
~ 3'7~
--`alO(P04)6F2 + 3Na2C03 ~ 25iO2 + ~120 6CaNaP04 + 2CaSiO~ + 3C02 -~ 2~F
Rhenania phosphate Rhenania phosphate has a phosphorus content of 11% and is soluble in basic ammonium citrate.
Iron ore containing phosphorus yields Thomas slag as a hy-product in the steel industry. Limestone and oxygen are adde~ to the molten iron ore, thus separating the slag on the sur-face of the mixture.
Thomas slag contains approximately 7...10% phosphorus, of which 90~ is soluble in a 2% solution of citric acid.
The process of treating phosphate rock with sulphuric acid is very complex and requires a high pressure, great accuracy and a great deal of energy. Another reaction product is toxic hydrogen fluoride. Sulphuric acid is not only toxic but also expensive, due to the complexity of its production process and the high input of energy required. Although superphosphate contains calcium sulphate, an excessive amount of calcium sulphate waste is also produced in the process, thus causing an environmental hazard.
When treating phosphate rock with sulphuric acid and water in order to produce phosphoric acid, the hazards are the same as mentioned ahove, with the exception that even more calcium sulphate waste is produced. In addition, the valuable micro nutrients and lanthanides are lost in the process.
Phosphoric acid can be regarded as a mere intermediate product, because its use as a fertilizer is very inconvenient.
Consequently, it is further processed into other fertilizers, such as triple superphosphate, as described above, or fertilizing compounds.
S
~_ 26350-7 The reactions oE phosphate rock with hydrochloric or nitric acid are uti:lized very ln~requently.
During heat treatment o-E phosphate rock, the substances contained in the rock are retained in the -Eertilizer. However, the required temperature of 1,200C is extremely high, involving very high energy consumption. In addition, the phosphorus in the end produc-~ i5 not water-soluble.
Thomas slag is one of the oldest phosphorus EertilizersO
It is, however, produced only by the steel industry, and only if the iron ore contains phosphorus. Another disadvantage of the process is that it causes considerable noxious odours.
The invention eliminates or considerably reduces -the previously mentioned hazards as follows:
- Consumption of energy remains remarkably low.
- No industrially produced inorganic acids are needed.
- There are no environmental hazards in the process, such as toxic reaction products, odour or waste products.
- The nutrient elements of phosphate rock are almost com-pletely retained in the fertilizer.
The present invention provides a method for producing a combined phosphorus fertilizer and soil conditioner which process comprises:
(a) heating an organic material selected Erom the group consisting of uncomposted bark waste, peat, waste pulp fibres and sawdust having a pH of less than 6 and a moisture content of at least 40% by weight to a tesnperature in the range of 40C to 120C
to produce an acidiEied, moist organic massi 7~4~
-4a~- 26350-7 (b) grlndlng p'hosphate rock to rl part:icLe s:i~e oE rlbOut 0.02 to 3m1n and, i:E the solubility of phosphorus in the rock in 2 citric acid is less than 10~ of total rock phosphorus, t'hen `heatin~ resulting phosphate rock particles to a temperature in the range of 50C to 800C, to produce phosphate rock particLes; and (c) admixing and reacting said moist organic mass with said phosphate rock particles to yield said fertilizer.
An Application of the method is described in detail below, with reference to the adjoining drawing which shows a schematic outline of an embodiment of -the method of the invention.
The organic material, consisting of uncomposted bark waste or pea-t, is fed from a feed silo, pos. 1, to the grinding unit, pos. 2. If waste fibre from a pulp or paper mill or sawdust is used in addition to or instead of t'he ma-terials men-tioned above, the organic ma-terial can be fed to the process directly from the tank, pos. 3. Waste fibre is understood as precipita-ted slurry from a water treatment station of a pulp or paper mill and thus contains mainly short wood fibres not suitabLe for pulp or paper production. This slu:rry always contains very fine particles of bark.
All the materials mentioned must be acidic, with a pH of less than 6, prefera'bly lower than 5.5. The reaction mass of bark, peat, cellulose was-te material or sawdust is`heated in the reac-tor furnace, pos. 4, to a temperature of 40 to 120C, depending on the 7~
- 5 ~ 26350--7 water content o~ the mass; t'he greater the w~ter ~ontc-nt, the hig'her the temperature, and the higher the temperature of the pnosphate rock, the Lower the temperature o~ the mass. This process corresponds to the process described in U.S. Patent 4,571,254 entitled "A method for producing fertilizers from wood ashes and softwood bark or from other wood waste ma-terial", with the exception that the water content of the fresh organic material should be 40~ at the minimum. This requirement ls no-t included in the production method described in ~.S. Patent 4,571,254.
After the reactor furnace, pos. 4, phosphate rock, either magmatic, metamorphic or sedimented in origin or a concen-trate of these rocks, is fed into the process. The rock is to ~e preprocessed in the following way: firs-t, the rock is ground in a grinder. pos. 2A, -to a particle size of 0.02 to 3 mm. The smaller -the particle size, the higher the content of phosphorus, soluble in water and/or in citric acid, in the fertilizer. The optimum size is 0.02 to 1 mm. After grinding, the rock is transferred to a rotating heating ~urnace, pos. 4A, in w'hich the surface tempera-ture is approximatel~ 800C. The par-ticles are rapidly heated to a temperature of 50 to 800C, with an optimum temperature of 400 to 500C. The optimum temperature depends on the quality of the phosphate rock and on its water content. The closer to t'he optimal temperature the reaction takes place, the higher the con-tent oE soluble phosphorus in water and/or in citric acid in the end product.
3 ~3 7~L~
If in i-ts natural state -the solubility o:E the phosphorus in the phospha-te rock in citric acid is at least oE 10 ~ (concen-tration of the citric acid 2 %), heating is unnecessary and the phosphate rock at a temperature of about 20~C is mixed with the heated acidic organic mass.
After this stage, the mass of phosphate rock and organic reaction mass from the reactor furnace, pos. 4, are allowed to collide and mix. Generally, the higher the pressure under which the phosphate rock was formed, the higher the temperatures must be, thus also leading to higher pressures at the mixing stage.
This results in partial or complete disintegration of the phosphate rock or its concentrate, due to the following factors:
1. Because the pH of the organic reaction mass is lower than that of the rock, the acidity of the mixture will tend towards a state of equilibrium. The lower the pH of the organic matter is, the stronger the chemical reaction between -the organic matter and the phospha-te rock will be, and the higher the content of phosphorus soluble in water and/or in citric acid in the fertilizer will also be.
2. Because the calcium and phosphorus contents are lower in the organic matter than in the phospha-te rock, the lower the calcium and phosphorus content of -the organic mass is, the stronger the chemical reaction between -them is, and also the higher the content of phosphorus soluble in water and/or phosphorus soluble in citric acid in the fertilizer.
The weight ratio of dry phosphate rock and fresn organic matter is 0.015..Ø65. The greater the amount of or~anic matter, the greater amount of the phosphorus in the rock or in its con-'7~
centrate is converted into phosphorus so:luble irl water and/or in citric acid. The time required fo:r the reaction i~ :L0 to 60 minutes, generally approximate.Ly 15 minutes. ~he longer the re-action time, the greater the amount o-E phosphorus in the rock or in its concentrate is converted into water-soluble form.
In addition to the organic waste materials mentioned above bark waste, peat, waste fibre from pulp or paper mill, or sawdust other equivalent organic matters can also be used as reagents.
After the reaction, the mass, the temperature o-f which is 90C, is cooled quickly in a cooler, pos. 5, to a temperature of 20 to 40C.
Finally, wood or bark ashes can be added, i~ necessary, from the tank, pos. 6, or nitrogen from tank, pos. 7, and the mass is granulated on the rollers, pos. 8, if desired, and ashes can be applied to the surface of the granules in the mixing tank, pos. 9, as in the process described in ~.S. Patent 4,571,254 mentioned above.
The process described in the invention thus imitates the disintegration process of phosphate rock taking place in nature.
The content oE phosphorus soluble in water and/or in citric acid is 0 to 95%, depending on the amount and characteris-tics of the organic matter and of phosphate rock as well as of the reaction time. The reaction product is monocaLcium phosphate (Ca(H2PO4)2), a phosphorus compound soluble in wate.r or phosphate of similar composition.
The energy consumption remains low, because the reaction occurs at a low temperature and because the organic reaction 7~
matter is not produced industrial:Ly. There are no environmental hazards; on the contrary, the process consumes organic matter tha-t is hazardous -to the environment. The nutrien-t Eractions contained in the phosphate rock are retained more completely -than in processes involving the use of inorganic acids, as completely as in heat treatment me-thods.
The combined phosphorus mulch fertilizer and soil con-ditioner can also be used as mulch, if desired. In this case, the solubility of the phospnorus is of no practical consequence.
Thus the content of phosphorus soluble in water and/or in citric acid can be low and the production process can be somewhat simplified: the reaction time can be short, and the temperature to which the phosphate rock is heated, can be low; heating can be omitted if the solubility of the phosphate in the citric acid of the phosphate rock amounts to at least 10 %.
~f' .
The weight ratio of dry phosphate rock and fresn organic matter is 0.015..Ø65. The greater the amount of or~anic matter, the greater amount of the phosphorus in the rock or in its con-'7~
centrate is converted into phosphorus so:luble irl water and/or in citric acid. The time required fo:r the reaction i~ :L0 to 60 minutes, generally approximate.Ly 15 minutes. ~he longer the re-action time, the greater the amount o-E phosphorus in the rock or in its concentrate is converted into water-soluble form.
In addition to the organic waste materials mentioned above bark waste, peat, waste fibre from pulp or paper mill, or sawdust other equivalent organic matters can also be used as reagents.
After the reaction, the mass, the temperature o-f which is 90C, is cooled quickly in a cooler, pos. 5, to a temperature of 20 to 40C.
Finally, wood or bark ashes can be added, i~ necessary, from the tank, pos. 6, or nitrogen from tank, pos. 7, and the mass is granulated on the rollers, pos. 8, if desired, and ashes can be applied to the surface of the granules in the mixing tank, pos. 9, as in the process described in ~.S. Patent 4,571,254 mentioned above.
The process described in the invention thus imitates the disintegration process of phosphate rock taking place in nature.
The content oE phosphorus soluble in water and/or in citric acid is 0 to 95%, depending on the amount and characteris-tics of the organic matter and of phosphate rock as well as of the reaction time. The reaction product is monocaLcium phosphate (Ca(H2PO4)2), a phosphorus compound soluble in wate.r or phosphate of similar composition.
The energy consumption remains low, because the reaction occurs at a low temperature and because the organic reaction 7~
matter is not produced industrial:Ly. There are no environmental hazards; on the contrary, the process consumes organic matter tha-t is hazardous -to the environment. The nutrien-t Eractions contained in the phosphate rock are retained more completely -than in processes involving the use of inorganic acids, as completely as in heat treatment me-thods.
The combined phosphorus mulch fertilizer and soil con-ditioner can also be used as mulch, if desired. In this case, the solubility of the phospnorus is of no practical consequence.
Thus the content of phosphorus soluble in water and/or in citric acid can be low and the production process can be somewhat simplified: the reaction time can be short, and the temperature to which the phosphate rock is heated, can be low; heating can be omitted if the solubility of the phosphate in the citric acid of the phosphate rock amounts to at least 10 %.
~f' .
Claims (15)
1. A method for producing a combined phosphorus fertilizer and soil conditioner which process comprises:
(a) heating an organic material selected from the group consisting of uncomposted bark waste, peat, waste pulp fibres and sawdust having a pH of less than 6 and a moisture content of at least 40% by weight to a temperature in the range of 40°C to 120°C
to produce an acidified moist organic mass;
(b) grinding phosphate rock to a particle size of about 0.02 to 3 mm and, if the solubility of phosphorus in the rock in 2%
citric acid is less than 10% of total rock phosphorus, then heat-ing resulting phosphate rock particles to a temperature in the range of 50°C to 800°C, to produce phosphate rock particles; and (c) admixing and reacting said moist organic mass with said phosphate rock particles to yield said fertilizer.
(a) heating an organic material selected from the group consisting of uncomposted bark waste, peat, waste pulp fibres and sawdust having a pH of less than 6 and a moisture content of at least 40% by weight to a temperature in the range of 40°C to 120°C
to produce an acidified moist organic mass;
(b) grinding phosphate rock to a particle size of about 0.02 to 3 mm and, if the solubility of phosphorus in the rock in 2%
citric acid is less than 10% of total rock phosphorus, then heat-ing resulting phosphate rock particles to a temperature in the range of 50°C to 800°C, to produce phosphate rock particles; and (c) admixing and reacting said moist organic mass with said phosphate rock particles to yield said fertilizer.
2. A process according to claim 1 wherein said bark waste, peat, waste pulp fibres or sawdust have a pH of less than 5.5 and a moisture content of at least 45% by weight, said phosphate rock is ground to a particle size of about 0.02 to 1 mm and, if re-quired, the phosphate rock particles are heated to a temperature in the range of 400°C to 500°C.
3. A method according to claim 1, wherein unheated phos-phate rock with a solubility of the phosphorus in citric acid of at least 10% is added to said acidified, moist organic mass with a pH of less than 6, a moisture content of at least 40%, and a tem-perature in the range of 40° to 120°C.
4. A method according to claim 1 wherein the weight ratio of dry phosphate rock to fresh organic material is in the range of 0.015 to 0.65.
5. A method according to claim 1, 2, 3 or 4, wherein the organic material is waste bark.
6. A method according to claim 1, 2, 3 or 4, wherein the organic material is peat.
7. A method according to claim 1, 2, 3 or 4, wherein the organic material is waste fibre from a pulp or a paper mill.
8. A method according to claim 1, 2, 3 or 4, wherein the organic material is sawdust.
9. A method according to claim 1, 2, 3 or 4, wherein the amount of phosphorus soluble in water or in citric acid in the fertilizer is regulated by the pH of the acidified, moist organic mass.
10. A method according to claim 1, 2, 3 or 4, wherein the amount of phosphorus soluble in water or citric acid in the ferti-lizer is regulated by calcium and phosphorus content of the phos-phate rock.
11. A method according to claim 1, 2, 3 or 4, wherein the amount of phosphorus soluble in water or citric acid in the ferti-lizer is regulated by the temperature to which phosphate rock particles are heated.
12. A method according to claim 1, 2, 3 or 4, wherein the amount of phosphorus soluble in water or citric acid in the ferti-lizer is regulated by the retention of the reaction.
13. A method according to claim 1, 2, 3 or 4, wherein the amount of phosphorus soluble in water or citric acid in the ferti-lizer is regulated by the weight ratio of the fresh organic mater-ial and the dry phosphate rock.
14. A method according to claim 1, 2, 3 or 4, wherein the amount of phosphorus soluble in water or citric acid in the ferti-lizer is regulated by the particle size of the crushed phosphate rock.
15. A method according to claim 1, 2, 3 or 4, wherein the solubility of the phosphorus in water or citric acid is allowed to remain low and thus the product is suitable for a mulch material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000520584A CA1287746C (en) | 1986-10-16 | 1986-10-16 | Production method of combined phosphorus fertilizer and soil conditioner |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000520584A CA1287746C (en) | 1986-10-16 | 1986-10-16 | Production method of combined phosphorus fertilizer and soil conditioner |
| FI864174A FI73659C (en) | 1986-10-16 | 1986-10-16 | Preparation process for combined phosphorus fertilizers and soil enhancers. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1287746C true CA1287746C (en) | 1991-08-20 |
Family
ID=25671125
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000520584A Expired - Lifetime CA1287746C (en) | 1986-10-16 | 1986-10-16 | Production method of combined phosphorus fertilizer and soil conditioner |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1287746C (en) |
-
1986
- 1986-10-16 CA CA000520584A patent/CA1287746C/en not_active Expired - Lifetime
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