RU2078031C1 - Method of charge preparing for phosphorus production - Google Patents

Abstract

FIELD: chemical technology, inorganic chemistry. SUBSTANCE: charge is composed of the ground phosphorus slag and coke (for phosphorus reduction) and phosphoric acid at the following ratio of components, wt.-%: phosphorus slag, 28-47; coke for phosphorus reduction, 8-12; phosphoric acid (90-96%), 45-60. EFFECT: decreased slime formation during charge processing to phosphorus in furnace. 4 cl

Description

 The invention relates to a technology for the preparation of phosphate raw materials, the process for the production of phosphorus, in particular to its agglomeration.

Known mixture [1] consisting of lump phosphorite (5 50 mm), quartzite (5 25 mm) and coke (5 20 mm). Before being fed into the oven, phosphorite is calcined at 700-1000 ^° C, coke and quartzite are dried at 300 ^° C.

 A disadvantage of the known charge is the need for its heat treatment, high yield of sludge when it is processed in a furnace for phosphorus (450 kg per 1 ton of phosphorus).

A known method of sintering phosphate materials by agglomerating them on the grate [2] is that phosphorite fines are mixed with quartzite, coke breeze in a predetermined ratio. The resulting mixture (mixture) is moistened, pelletized and sintered on the grate at 1250 1300 ^o C. The resulting cake is crushed to the required size. Then the agglomerate together with box coke and quartzite is fed into the furnace as a mixture to produce phosphorus.

 A disadvantage of the known mixture is the need for high-temperature processing of the mixture. When processing agglomerated agglomerates. charge in the furnace there is a large yield of sludge 350 kg per 1 ton of phosphorus.

 Known charge [3] for the agglomeration of phosphate raw materials containing phosphate raw materials, coke, quartzite and slag phosphorus production in the following ratio of components, wt.

Coke 5.5 6.5
Phosphorus slag 3 10
Phosphorus raw materials The rest is up to 100
The disadvantage of this method is that it requires thermal preparation of the mixture to 1200 1300 ^o C and a large yield of sludge (350 kg per 1 ton of phosphorus) when processing the mixture in the furnace to phosphorus.

A known method of agglomeration of phosphate raw materials [4] consisting in the fact that in order to increase the strength of the agglomerate, a mixture of phosphoric acid and phosphate raw materials in the ratio of (0.1 0.12) 1, which is dipped, and then the obtained granules are mixed with quartzite and coke and again doused in the presence of water and then agglomerated. The agglomerate is crushed to a fraction of 10 70 mm, mixed with quartzite and coke and fed to the furnace to produce phosphorus. The disadvantage is the thermal preparation of the charge (1200 1300 ^o C) and a large yield of sludge (300 kg per 1 ton of phosphorus) when processing the charge in the furnace to phosphorus.

A known method (prototype) of agglomeration of phosphate raw materials [5] is that during agglomeration of phosphorite fines, the resulting return (small agglomerate) is not returned, as usual, in the process of agglomeration, but is mixed with 45% phosphoric acid supplied in an amount of 10 wt. . briquetted at a pressure of 20 30 MPa and heat treated at 300 400 ^o C.

 The disadvantage of this method is that it requires press equipment and heat treatment of briquettes, as well as a large output of sludge (350 kg per 1 ton of phosphorus) when processing briquettes in a furnace for phosphorus.

The underlying cause of the formation of large quantities of sludge is the following. When phosphorus is electrically sublimated in electric furnaces, the average temperature of phosphorus sublimation is about 1800 ^o C, however, when the furnace is operating on phosphate raw materials, local overheating up to 2500 ^o C and even higher takes place. This is explained by the fact that the furnace does not fully operate in the “resistance” mode, and in some places there is an arc mode in which the reaction mass is heated above the required temperature, i.e. between the precipitation and corona electrodes, a breakdown occurs. The result of local overheating is the intensive evaporation of a number of components of the phosphate feedstock, which then condense and fall into commercial phosphorus, which leads to the large amount of sludge in the latter. In addition, the formation of organophosphorus compounds occurs at high temperatures, which also enter the marketable phosphorus, which causes pollution of its border.

 In order to simplify the phosphate raw material sintering and reduce sludge evolution during the processing of the charge in the furnace to phosphorus, the charge is composed of phosphorus slag and coke, as well as phosphoric acid, ground to a fraction of 0 mm, in the following ratio of components, wt.

Phosphorus Slag 28 47
Coke 8 12
Phosphoric Acid (90.0 96.0) 45 60
Phosphoric slag and coke are pre-mixed and ground to a particle size of 1.0-0.0 mm, then phosphoric acid is added and mixed. The mixture is molded and held in air for 1 to 2 hours until solidified, and then ground to a particle size of 5–70 mm.

.The resulting mixture in physical and chemical characteristics is not inferior to the known mixture. So, when testing it in a standard drum, the yield of fines -0.5 mm is 5 and the output of the fraction +5 mm is 80.0
The content of the main component P ₂ O ₅ is 28 37% acidity module

.

 A sharp decrease in the formation of sludge (up to 50 kg per 1 ton of phosphorus) during the processing of this charge by the electrothermal method allows to obtain especially pure phosphorus, especially for such components as arsenic and heavy metals.

Example 1. Take phosphoric slag containing, by weight. but. 40.8; CaO 49.2; MgO 2.68; Al ₂ O ₃ 2.06; P ₂ O ₅ 1.0 in an amount of 80 kg. Metallurgical coke in the amount of 20 kg is added to the slag. Slag and coke are crushed in a ball mill to a particle size of 1.0 0 mm. 100 kg of concentrated (92) phosphoric acid are added to the ground mixture (slag and coke) and mixed. Get the solution in color and properties, reminiscent of a concrete solution. The solution is distributed in the forms where it hardens within 1 hour. Then, the formed material is finished on the jaw crusher to a particle size of 5 - 70 mm.

The resulting piece has a strength of 0.5 mm 5.0% + 5.0 mm 80 contains P ₂ O ₅ 30.0 wt. acidity modulus M _to 0.8.

 The charge in the amount of 200 kg is tested in an ore-thermal furnace with a capacity of 200 kW. For technical reasons (the charge should be partially located with the loading device), it is possible to recover 100 kg of the charge from such a quantity of charge. Received 11 kg of phosphorus and 0.520 kg of sludge.

Example 2. Take phosphoric slag, coke and phosphoric acid, as in example 1, but in the following quantity, kg:
Phosphorus Slag 56
Coke 24
Phosphoric Acid 120
The preparation of the mixture is the same as in example 1. The resulting piece has strength,
-0.5 mm 6
+5 mm 78
P ₂ O ₅ in piece 37
When recovering 100 kg of the charge, 13 kg of phosphorus and 0.65 kg of sludge are obtained.

Example 3. The source material and the preparation of the mixture are the same. Materials for the preparation of the charge taken in the following quantity, kg:
Slag 94
Coke 16
Phosphoric Acid 90
The resulting piece has strength,
-0.5 mm 6.5
+5 mm 77
The mixture contains P ₂ O ₅ in the amount of 28
When recovering 100 kg of the mixture receive phosphorus 10 kg and sludge of 0.5 kg.

 It was experimentally established that when using phosphoric acid in a charge of less than 45 wt. a sufficiently strong piece does not work and its further use in the furnace is impossible.

Example 4. The materials and preparation of the mixture are the same as in example 1, but the ratio of materials is as follows, kg:
Slag 106
Coke 14
Phosphoric Acid 80
The resulting piece is fragile, crumbles, is not suitable for use in the restoration of phosphorus from it by an electrothermal method.

 When using phosphoric acid in a charge of more than 60, a piece does not work out, the mass spreads, and its use in the furnace is impossible (example 5).

Example 5. The materials and preparation of the charge are the same as in example 1. For the preparation of the charge serves materials in the following quantity, kg:
Slag 49
Coke 21
Phosphoric Acid 130
Prepared by the method as in example 1, the mixture spreads, does not harden.

 For use in the electrothermal conversion is not suitable. The reason for this is, apparently, an excess of acid compared with the amount necessary for the reaction with a slag-coke mixture.

 Thus, it was found that the proposed mixture for the production of phosphorus provides a sufficiently strong phosphate lump, when used in the electrothermal redistribution of sharply reduced sludge output. A comparative table is given (see the end of the text).

Claims (3)

 1. The method of preparation of the mixture to obtain phosphorus, including the preparation of the mixture by mixing phosphorus-containing raw materials with coke and phosphoric acid, characterized in that as phosphorus-containing raw materials use phosphoric slag from a phosphorus furnace in the following ratio of components, wt. Phosphorus Slag 23 47
Coke 8 12
Phosphoric acid 45 60
2. The method according to p. 1, characterized in that the phosphorus slag and coke are pre-mixed and subjected to grinding to a particle size of less than 1 mm  3. The method according to p. 1, characterized in that phosphoric acid is added to the ground slag and coke and mixed.  4. The method according to p. 1, characterized in that the mixed charge is molded and held in air until solidified, and then crushed to a particle size of 5 - 70 mm

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