JPS6071506A - Manufacture of phosphate from natural phosphate rock - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing desired phosphates, such as magnesium ammonium phosphate, ammonium phosphate, polyphosphates and birophosphates, from naturally occurring phosphate rocks.

These compounds are used as fertilizers (alkali metal phosphates, magnesium ammonium phosphates, and ammonium phosphates) and as detergent builders and water treatment agents (alkali metal pressure phosphates, polyphosphates, birophosphates, and metaphosphates). ) is of considerable economic importance. The process of the present invention provides a cheaper and more rapid method for the production of various phosphate salts. In a preferred embodiment of the invention, by-products are recycled to reduce the amount of unwanted product that requires disposal and the potential for contamination.

The composition of naturally occurring phosphate rocks varies depending on their source. The main constituent of some rocks, eg Florida stone, is calcium phosphate, while the main constituent of other rocks, eg palandite, is iron and/or aluminum phosphate. Other rocks, such as Christmas Island O grade,
is a complex mixture of calcium, aluminum and iron phosphates. The relative proportions of calcium phosphate, iron phosphate, aluminum phosphate and other components in rocks from different sources are subject to wide variations, as is well known to those skilled in the art. The method of the invention allows the use of naturally occurring phosphate rocks as raw materials, which was not possible with prior art methods.

Phosphate salts produced include, but are not limited to, those listed below. Namely, disodium orthophosphate and -sodium pentasodium tripolyphosphate sodium metaphosphate and its polymers Tetrasodium birophosphate Sodium hydrogen phosphate Ammonium Magnesium ammonium phosphate Potassium salts corresponding to the above substances.

Sources of alkali metal orthophosphates include, but are not limited to: (1) Known methods for extracting naturally occurring phosphate rocks containing iron and aluminum phosphates with a sodium hydroxide solution.

(2) A naturally occurring phosphate rock containing iron and aluminum phosphates is disclosed in the inventor's Australian patent application FG066 filed on August 4, 1983.
A method of extraction with a solution of alkali metal carbonates and hydroxides, as disclosed in No. 2.

(3) Inventor's Australian Patent Application No. 2850
No. 7/84, any naturally occurring phosphate rock can be combined with an alkali metal carbonate or one of the present invention.
In one form, trisodium orthophosphate is converted to disodium or -sodium orthophosphate by carbonation in a controlled stream.

These phosphates are separated by cooling and carbonated)
It is believed that the reactions that occur once a solution of IJum remains are represented by the following simplified chemical reaction.

2Na! 3PO4+ 002 + H2O→2 Na2
HPO4+N&2003 and Na3PO4+ 002 + H2O−+NaH2PO
4+2 NaHOO3 In another form of the invention,
A mixture of disodium phosphate and -sodium phosphate is produced by the above reaction and then heat treated to produce trisodium citripolyphosphate.

2 Na2HPO4+ NaH2PO4→IJa51'
3o10 + 2H2O In a sixth form of the invention,
Orthophosphoric acid) IJum is treated with carbon dioxide and ammonia to produce sodium ammonium hydrogen phosphate and sodium carbonate. Sodium ammonium hydrogen phosphate is separated from sodium carbonate and then heat treated to form sodium metaphosphate or its polymer. The simplified form of the chemical reaction that occurs is believed to be represented by the following chemical reaction: H2O+Na3PO4+ NH3+002 →NaNH
4HPO4+ Na2003Na NH4PO4+ Heat→
NaPO3+NH3+H2O In a fourth form of the invention, sodium orthophosphate is reacted with ammonia and carbon dioxide at low temperatures to form a compound that approximates the chemical formula of sodium carbonate and triammonium phosphate.

The latter is separated from the IJ solution and then heated to form triammonium or -ammonium phosphate. A simplified form of the chemical reaction that is believed to occur is shown below.

2 Na1PO4+ 6 NH3+ 3aoz 13H2
0-+2 (NH4)3PO4+ 3 Na2003(
MNa2O03 (+ heat → (NH4)2HPO4+ NH
3(NH4)H'PQa+heat→1[4H2PO4+ 1
1H3 In a fifth form of the invention, a solution of sodium phosphate is reacted with magnesium carbonate, carbon dioxide and ammonia to produce magnesium ammonium phosphate and sodium carbonate. A simplified form of the chemical reaction that is believed to occur is shown below.

2 Na3PO4+ 2 MgO03+ 002 +
NHR+ H20→2 MgNH4,PO4+ 3 N
a2003 Although the above examples relate to sodium orthophosphate, it should clearly be understood that the invention also applies to corresponding potassium compounds.

Advantages Conventional techniques in the alkaline treatment of phosphate rocks result in the production of trisodium orthophosphate (e.g. Rothbaum &Reeve"R
ecovery of alumina and ph
osphate fromChristmas Engineering 1an
d OPhosphate, N, Z, Journ
alof 5science+ Vol, II r N
O-4r DeOeml)er+1968).

Sodium orthophosphate is a valuable product with a limited market, and several methods have been developed to convert it into other products. For example, my Australian Patents Nos. 464,459 and 486,139 for making magnesium ammonium phosphate; my New Sealant Patents Nos. 163,118 and 486,139 for making ammonium phosphate; The economics of process 1 relies on the sale of by-products such as sodium sulfate produced with magnesium ammonium phosphate. In the process of the present invention, magnesium ammonium phosphate can be produced in a regenerative manner that does not rely on the production of by-products.

Furthermore, (1) When producing magnesium ammonium phosphate from trisodium phosphate, all the sodium is recycled to produce more trisodium phosphate. Significant consumption of purchasing alkali metal carbonates or hydroxides (besides the need to compensate for impairment losses) is avoided.

(2) Since no by-products such as sodium sulfate are produced, the overall economics are not dependent on the sale of by-products.

(3) The economics of the second method is that naturally occurring magnesium carbonates, such as magnesite or lomite, can be used, thus eliminating the expense of preparing soluble magnesium compounds such as magnesium sulfate. is affected by the large amount of substances that must be heated, cooled and evaporated. In the presently disclosed method, this method can be simplified.

Conventional methods for producing ammonium phosphate include sulfuric acid, D
The process involves pickling the IJ phosphate rock, separating the resulting calcium sulfate from the phosphorus starch, and then reacting the phosphoric acid with ammonia.

Some advantages of the new method of the present invention over conventional methods can be summarized as follows.

(1) Ammonium phosphate can be produced from naturally occurring phosphate rock by a regenerative method in which the only raw materials required are phosphate rock and ammonia. No auxiliary ingredients such as sulfuric acid are required.

(2) Since an alkaline treatment system is included, the cost of acid-resistant equipment is eliminated.

(3) The amount of waste material, such as gypsum, that needs to be disposed of is reduced.

(4) The process of the present invention enables the production of ammonium phosphate from naturally occurring iron and aluminum phosphates, which was hitherto not possible with conventional acid treatment methods.

In addition to magnesium ammonium phosphate and ammonium phosphate, the process of the invention produces a series of valuable sodium and potassium phosphates, such as pentasodium tripolyphosphate, potassium dihydrogen phosphate and sodium metaphosphate. be able to.

The conventional method of producing these compounds is to produce high purity phosphoric acid from elemental phosphorus or by reacting special grades of phosphate rock with sulfuric acid. The wet high purity phosphoric acid is then reacted with an alkali metal carbonate or hydroxide to produce the desired compound.

The production of elemental phosphorus is expensive, requires large amounts of energy, and is prone to pollution.

Wet phosphoric acid is also expensive to produce high purity phosphoric acid;
In the process of the present invention, which also produces large amounts of unwanted by-product gypsum, high purity alkali metal phosphates are produced directly from phosphate rock and alkali metal carbonates and hydroxides. Alkaline processing methods do not introduce impurities into the solution as do acidic processing methods. (by extraction of low-grade rocks such as Christmas Island Class C, or by carbonic acid)
Trisodium phosphate produced by melting IJum has high purity and can be obtained at low cost. The method of the present invention includes:
Excess sodium required for the production of polyphosphoric acid and cypyrophosphate is removed in a form that can be reused for the production of trisodium phosphate. The method of the invention further has the advantage that expensive acid-resistant structures are not required, since the processing is carried out in an alkaline environment.

EXAMPLES The invention is illustrated by the following non-limiting examples.

Example 1 Trisodium orthophosphate extracted by alkaline treatment of Christmas Island C-class rock was dissolved at 60°C in dilute carbonate and sodium bicarbonate solution recycled from a previous operation.

Bubble carbon dioxide into the solution and gradually increase the temperature to 30°C.
The pH of the solution decreases while it is lowered to ℃.
Measured with an electrode, it dropped from 13.5 to 9.2.

Under these conditions crystals of sodium orthophosphate (essentially di-orthophosphate with a Na:P ratio of 2:1) IJ
um) was generated. If the voice was not adjusted, N
Crystals of sodium orthophosphate, in which crystals with an a:P ratio close to 3:1 were desired to be produced, were separated from the solution, and then the remaining solution was cooled to 20° C. to precipitate sodium carbonate crystals. The residual solution containing sodium carbonate, sodium bicarbonate and some sodium phosphate was recycled to dissolve more trisodium orthophosphate.

By these methods, virtually all of the phosphate in trisodium orthophosphate could be converted to the disodium form, while one-sixth of the sodium was recovered as sodium carbonate, which was could be reused for alkaline extraction of rocks.

Example 2 Orthophosphate disodium salt produced by the method described above was treated with recycled sodium carbonate and bicarbonate (IJ)
Carbon dioxide was bubbled into the solution, and the temperature was gradually lowered to 20°C.
During that time, IJum's insensitivity dropped from 9.2 to 7.5 as measured by one prologue. Under these conditions, crystals of sodium orthophosphate (essentially a mixture of disodium and monosodium phosphate) were formed with a sodium to phosphorus ratio of Na:P=5 to 3.

The crystals were removed, washed with water and then heat treated to give pentasodium tripolyphosphate Na5P3016. The remaining solution, which essentially contains sodium carbonate and sodium bicarbonate, was cooled to 10°C. Crystals of the two types of carbonate mixture were precipitated. The remaining carbonate solution, which contained traces of sodium phosphate, was recycled to obtain more trisodium orthophosphate.

By these methods, substantially all of the phosphate in trisodium orthophosphate was converted to pentasodium tribo-IJ IJ phosphate. 4/9 of sodium is carbonated) IJ
They were able to recover it in the form of umum and reuse it for alkaline extraction of the original rock.

Example 3 Disodium orthophosphate prepared by the method summarized in Example 1 was heated to
Heat treated for hours.

By this method, all disodium orthophosphate could be converted to tetrasodium birophosphate according to the reaction described below.

2 Na2HPO4+Heat→Na4P2O7+ H20 Example 4 Disodium orthophosphate prepared by the method summarized in Example 1 was dissolved in recycled sodium carbonate solution at 50°C. Carbon dioxide and ammonia gas were introduced into the solution in equimolar proportions after preheating to 40-50° C. to avoid excessive cooling. The temperature gradually decreases to 1
The temperature decreased to 5° C. and the pH, measured by a sodium-insensitive electrode, decreased to 7.5.

Crystals of microcosmic salt Ha NH4HPO4 were separated from the solution, washed, and then heat treated to obtain sodium metaphosphate. The expelled ammonia was reused to produce microcosmic salts.

The remaining solution after crystallizing the microcosmic salt was heated to 5°C.
The mixture was further cooled to 50°C and the mixed crystals of sodium carbonate and sodium bicarbonate were removed. The remaining sodium carbonate solution, containing some phosphorus and ammonia, was recycled to dissolve more trisodium phosphate.

Example 5 Trisodium orthophosphate extracted from Christmas Island O-class rock was dissolved at 70°C, then cooled and carbonated in solution to 20°C and pH 9.2.

Disodium orthophosphate precipitated. Sodium carbonate is crystallized from the solution by cooling to 10°C and then
The reused disodium orthophosphate was redissolved and then treated at 60° C. by introducing more carbon dioxide and ammonia gas through a separate diffuser. The amounts of carbon dioxide and ammonia added were calculated based on 1.05 moles of each gas for each mole of IJium orthophosphate.

The solution is then cooled to 15°C, resulting in microcosmic salts (
Crystals of sodium ammonium hydrogen phosphate) precipitated. The microcosmic salts were filtered off, washed and heated to 600° C. to drive off ammonia and form sodium hexametaphosphate.

Example 6 A microcosmic salt produced by the method summarized in Example 4 was dissolved in a recycled sodium carbonate and ammonium carbonate solution at 30°C, and carbon dioxide and ammonia were added in gaseous form. .

The temperature gradually decreased to 5°C, while the temperature increased to 8°C as measured by temperature-insensitive electrodes.

Crystals resembling triammonium phosphate are separated from the solution,
After washing, a heat treatment was then applied to obtain triammonium phosphate to drive off the ammonia and recover it for reuse.

The remaining solution was evaporated and then cooled to 20°C to recover the sodium carbonate. Any remaining solution was recycled to dissolve more microcosmic salts.

The carbon dioxide and ammonia driven off during evaporation were also recycled. By these methods, substantially all of the phosphorus in the original trisodium phosphate could be converted to ammonium phosphate. At the same time, virtually all the sodium was recovered in the form of sodium carbonate, which could be used in the alkaline extraction of the original phosphate rock.

Example 7 A microcosmic salt prepared by the method summarized in Example 4 is dissolved in a dilute recycled carbonate solution of sodium and ammonium, followed by an ammonia-added solution of magnesium bicarbonate and carbon dioxide. Mixed at 40°C in the presence of.

produced a precipitate of magnesium ammonium phosphate,
The ratio of 1 to 8 was adjusted by adding ammonia and carbon dioxide to avoid precipitation of the magnesium phosphate at high temperatures and to keep the magnesium bicarbonate in solution due to the presence of ammonia. The magnesium ammonium phosphate was separated, washed, and heat treated to remove the water. The remaining solution was cooled to 20°C to recover sodium carbonate. Since the residual sodium carbonate solution contained some ammonium bicarbonate, this solution was recycled to dissolve more microscopic salt.

Example 8 Dipotassium orthophosphate was produced in the same manner as the method for producing disodium orthophosphate (Example 1). This compound was heated to 300° C. to drive off water to produce tetrapotassium pyrophosphate.

It will be clearly understood that the invention is not limited to the particular embodiments described above.

Agent Asamura Hajime

Claims (1)

[Claims] (1) Naturally occurring phosphate is treated under alkaline conditions to produce a substance containing sodium orthophosphate and/or potassium orthophosphate, and the substance is carbonated in solution. Naturally occurring phosphate or G
'Method of producing the desired phosphate. (2) The desired phosphate is disodium orthophosphate and sodium orthophosphate, pentasodium tripolyphosphate, sodium metaphosphate and its polymers, tetrasodium birophosphate, ammonium phosphate, ammonium sodium hydrogenphosphate, The method of claim 1 selected from the group consisting of magnesium ammonium phosphate and their corresponding potassium salts. (3) Trisodium orthophosphate or tripotassium orthophosphate extracted by alkaline treatment of phosphate rock is treated with carbon dioxide in an aqueous solution to produce disodium orthophosphate or dipotassium orthophosphate. 2. The method of claim 1, wherein the phosphate is recovered from a carbonated solution by crystallization. (4) Produce disodium orthophosphate by the method described in claim 6, and treat disodium orthophosphate with carbon dioxide in an aqueous solution to obtain sodium orthophosphate and disodium orthophosphate. A method for producing a mixture of sodium orthophosphate and disodium orthophosphate, comprising forming a mixture of sodium orthophosphate and disodium orthophosphate, and recovering said mixture from solution by crystallization. (5) Producing crystals of sodium orthophosphate and disodium orthophosphate by the method described in claim 4, washing the crystals with water, and then heat-treating the washed crystals. A method for producing pentasodium tripolyphosphate, which comprises producing pentasodium tripolyphosphate. (6) Produce crystals of disodium orthophosphate or dipotassium orthophosphate by the method described in claim 6, and heat-treat the crystals to obtain tetrasodium birophosphate or tetrapotassium birophosphate. A method for producing tetrasodium pyrophosphate or tetrapotassium pyrophosphate. (7) Producing sodium orthophosphate by the method set forth in claim 3, and carbonating the sodium orthophosphate)
A method for producing ammonium sodium hydrogen phosphate, which comprises dissolving it in a solution of ammonium hydrogen phosphate, treating the solution with carbon dioxide and ammonia gas, and recovering crystals of ammonium sodium hydrogen phosphate from the treated solution. (8) Fi by the method described in claim 7.
After producing IJ sodium ammonium hydrogen phosphate,
A method for producing sodium metaphosphate, which comprises heat-treating sodium ammonium hydrogen phosphate to produce sodium metaphosphate. (9) J) by the method described in claim 7
IJ Sodium ammonium hydrogen phosphate is prepared by dissolving sodium ammonium hydrogen phosphate in a solution of sodium carbonate and ammonium carbonate, treating the solution with carbon dioxide and ammonia gas, and then adding the treated solution to triammonium syphosphate. A method for producing triammonium phosphate, which comprises recovering triammonium phosphate. 0Q Triammonium phosphate is produced by producing triammonium phosphate by the method set forth in claim 9, and heat-treating triammonium phosphate to produce triammonium phosphate. Method, alpha power: Producing thorium ammonium hydrogen phosphate by the method described in claim 7, dissolving sodium ammonium hydrogen phosphate in a sodium carbonate solution, and then adding bicarbonate in the presence of carbon dioxide. A method for producing magnesium ammonium phosphate, which comprises adding an ammonia-added solution of magnesium to form a precipitate of magnesium ammonium phosphate. (6) The method of claim 1'1, carried out in about 7 - days. 01 Sodium hexametaphosphate is produced by producing sodium ammonium hydrogenphosphate by the method set forth in claim 7, and then heat-treating the sodium ammonium hydrogenphosphate to produce sodium hexametaphosphate. How to manufacture. 04. A product produced by a method according to any of the preceding claims.