RU2078032C1 - Method of preparing the charge to phosphorus sublimation - Google Patents

Abstract

FIELD: chemical technology, inorganic chemistry. SUBSTANCE: method involves making the charge from phosphate fines (fraction size below 10 mm), metallurgic coke and quartzite, mixing with binding agent, briquetting and thermic treatment of briquets. Charge is mixed with binding agent on acid or alkaline base in the presence of addition of monosodium phosphate or monopotassium phosphate, or trisodium phosphate taken at amount 0.1-0.4% of binding agent mass. Briquetting is carried out by pressing under specific pressure 20-44 MPa. Size of the formed briquets is 70 mm. Thermic treatment is carried out at 150-300 C for 30-60 min. EFFECT: improved method of charge preparing. 2 cl

Description

 The invention relates to techniques for the preparation of raw materials for the electrothermal production of phosphorus.

 A known method of preparing the mixture for sublimation of phosphorus (Ershov V.A. Belov V.N. Technology of phosphorus, L. Chemistry, 1979, S. 72-81, 103-167), which consists in the fact that commodity ore-fuel raw materials before feeding for drying or firing, and also after that sorted, separating fines (less than 10 mm) from phosphorite, less than 5 mm from quartzite and coke. Screening of little things is classified as waste. The upper limit is taken for the size of phosphorite 70 mm, quartzite 70 mm and coke 20 mm.

 It is known that the rate of phosphorus reduction process is directly proportional to the charge surface and is determined by the nature of the starting materials, temperature, acidity modulus, i.e. the higher the surface of the components per unit volume, the higher the recovery rate. Common features of the known technical solution and the claimed is the preparation of a mixture of phosphorite, quartzite and coke.

Площадь поверхности средней гранулы составила
S=πD $\genfrac{}{}{0ex}{}{\text{2}}{\text{с.в.}}$ = 3,14•36²= 4069 мм²= 40,7 см².
Объем гранулы

Удельная поверхность гранулы, отнесенная к ее объему, составит

что является малой величиной.The mixture according to the known method consists of 75% phosphorite, 10% quartzite and 15% coke. Therefore, the weighted average diameter of the granules of the charge is

The surface area of the middle granule was
S = πD $\genfrac{}{}{0ex}{}{\text{2}}{\text{sv}}$ = 3.14 • 36 ² = 4069 mm ² = 40.7 cm ² .
Granule volume

The specific surface of the granule, referred to its volume, will be

which is a small quantity.

 It is necessary in the recovery zone to increase the specific surface by reducing the size of the granules, which is not possible in the known method.

A known method of granulation of phosphorite fines (ed. St. USSR N 657838, class C 01 B 25/01, Bulletin N 15, 1979, p.16) by pelletizing or briquetting in the presence of acid phosphates of alkali or alkaline earth metals binder with their ratio (1-5): 1. Acidic phosphates of alkali and alkaline earth metals are taken in an amount of 0.5-5.0% plumb phosphorite fines at pH 3-6. Briquettes are obtained by pressing at a specific pressure of 50 MPa, the maximum briquette size is 70 mm. Briquettes are heat treated at a temperature of 700 ^o C.

Disadvantage: high heat treatment temperature, high specific pressing pressure, the mixture of briquettes when it reaches high temperatures in the recovery zone has a small specific surface
S = 3.14 • 7 ² = 154 cm ² ,
V = 179 cm ³ ,
S: V = 154: 179 = 0.86 cm ^-1 .

The weighted average diameter of the charge is D _st. = 7 cm.

A known method (prototype) of agglomeration of phosphate rock fines (ed. St. USSR N 230795, class 121, 25/02, BI N 35, 1968) by mixing phosphorite with a silicon-containing material, roasting this mixture at 750-950 ^o C, further grinding this mixture and mixing with powdered coal or coke. Next, the mixture is moistened, molded, receiving briquettes of size 70 mm, and subjected to thermal treatment. Water-heat treatment is carried out in steaming chambers at a steam temperature of 80-90 ^o C for 2-3 hours or in autoclaves at 170 ^o C and a pressure of 2-8 atm.

Целью изобретения является увеличение поверхности компонентов шихты в восстановительной зоне печи.Disadvantage: the difficulty of heat treatment of briquettes is firing, steaming, at temperatures of phosphorus reduction, the surface of the mixture of these briquettes is low, the specific surface

The aim of the invention is to increase the surface of the components of the charge in the recovery zone of the furnace.

The goal is achieved in that the surface of the charge in the reduction zone of the furnace is regulated in the following way: make up the initial charge of phosphorite, quartzite, coke with a particle size of 0-10 mm, mix with a binder on an acid or alkaline basis with the addition of from 0.1 to 0.4 % of the weight of the binder monosodium phosphate or monopotassium phosphate or trisodium phosphate, briquetted at a specific pressure of 20-44 MPa, dried at a temperature of 150-300 ^o C for 30-60 minutes, briquettes with crushing strength above 10.0 MPa and a maximum size of 70 mm are obtained . Briquettes are loaded into the furnace and, upon reaching the recovery zone of phosphorus, they are destroyed into the initial fractions of the components (i.e., the briquettes are destroyed by themselves due to the cessation of the adhesion forces between the particles).

Example 1. Take screenings 0-10 mm of phosphorite, quartzite and coke, make up a mixture of 75% phosphorite, 10% quartzite, 15% coke. The mixture is moistened to 3%, 5.0% of the complex lignosulfonate is added and 0.4% of the amount of trisodium phosphate lignosulfonate is added, mixed thoroughly. The mixed charge is pressed on a hydraulic press PSU-10-50 in a mold of ⌀70 mm with a specific pressing force of 44 MPa. The briquettes are subjected to heat treatment: dried at a temperature of 300 ^o C for 60 minutes The crush strength of the briquette is determined to obtain (250-300) kg / cm ² .

, что в 7,7 раза выше, чем в известном способе.Briquettes on a special stand are installed in a laboratory shaft electric furnace, nitrogen is supplied and heated at a rate of temperature rise corresponding in time to its rise when the charge descends in an industrial ore-thermal furnace. When the temperature exceeds 1200 ^o C, the briquettes decompose into the initial fractions of the components of the mixture. In this case, the weighted average diameter of the charge granule D _r.v. = 4.7 mm ≈ 0.47 cm, the surface of the granule S = 0.69 cm ² , the volume of the granule V = 0.054 cm ³ . The volume of the granule in relation to the volume of the granule by a known method is reduced by 24.4: 0.054 = 452 times. Therefore, the surface of the mixture according to the proposed method in the volume occupied by the granule according to the known method, will be 0.69 • 452 = 312 cm ² . Or the specific surface of the mixture according to the proposed method (the surface assigned to an equal volume by the known method) is

that is 7.7 times higher than in the known method.

The volume of the granule in relation to the volume of the granule of the prototype decreases by 179: 0.054 ≃ 3300 times. The surface of the mixture according to the proposed method in the volume of granules according to the prototype will be 0.69 • 3300 ≃ 2200 cm ² . Or, the specific surface area of the charge according to the proposed method (the surface assigned to an equal volume according to the prototype) is 2200: 179 = 12.3 cm ^-1 , which is 14.3 (12.3: 0.86) times higher.

. Удельная поверхность

, выше, чем по прототипу, в 2,1:0,86=2,5 раза.Example 2. As in example 1, the mixture is prepared, moistened, 5% of the complex lignosulfonate and 0.1% of the amount of trisodium phosphate lignosulfonate are added, mixed. The mixed charge is pressed on a hydraulic press in the mold ⌀ - 70 mm with a specific pressing force of 20 MPa. The briquettes are dried at a temperature of 150 ^o C for 30 minutes Crush briquettes are tested, get 150 kg / cm ² . Then the briquettes are tested, as in example 1, when heated. At temperatures above 1200 ^o C, the briquettes scattered by 25%. At the same time, D _st. = 28.11 mm = 2.8 cm, S = 24.8 cm ² , V = 11.6 cm ³ . The surface of the mixture according to the proposed method in the volume of the granules by the known method is S = 52.1 cm ² . The specific surface area of 52.1: 24.4 = 2.13 cm ^-1 higher than in the known method. The surface of the mixture according to the proposed method in the volume of granules according to the prototype is

. Specific surface area

, higher than the prototype, 2.1: 0.86 = 2.5 times.

Example 3. As in example 1, the mixture is prepared, moistened, complex lignosulfonate is added, but trisodium phosphate is added in an amount of 0.25% of the amount of lignosulfonate. Briquetted at a specific pressing pressure of 32 MPa. The briquettes are dried at a temperature of 225 ^o C for 45 minutes Get briquettes crushing strength of 200 kg / cm ² . Briquettes, as in example 1, are tested when heated.

At temperatures above 1200 ^o C briquettes were scattered on a 50% D Thus obtained _d.s. = 2 cm, S = 12.6 cm ² , V = 4.4 cm ³ .

. Поверхность шихты по предлагаемому способу в объеме гранулы про прототипу составляет

Удельная поверхность

, что в 2,9:0,86=3,4 раза выше, чем по прототипу.The surface of the mixture according to the proposed method in the volume of the granules by the known method was S = 69.3 cm ² . The specific surface of the mixture in the volume of the granule by a known method

. The surface of the mixture according to the proposed method in the volume of granules about the prototype is

Specific surface area

, which is 2.9: 0.86 = 3.4 times higher than the prototype.

 The preparation of the mixture for sublimation of phosphorus by the proposed method with parameters above or below the specified limits is limited by the specific surface area of the mixture in the recovery zone: below the lower limit - in a known manner, above the upper limit by the indicators of example 1.

Claims (2)

1. The method of preparing the charge for sublimation of phosphorus, including its compilation of phosphate fines fraction up to 10 mm, metallurgical coke and quartzite, mixing with a binder, briquetting and heat treatment of briquettes, characterized in that the mixture is mixed with a binder on an acidic or alkaline basis in the presence of additives monosodium phosphate, or monopotassium phosphate, or trisodium phosphate, taken in an amount of 0.1 to 0.4 by weight of the binder, and briquetting is carried out by pressing at a specific pressure of 20 44 MPa to obtain briquettes of 70 mm in size and thermal Botko carried out at 150 - 300 ^o C for 30 to 60 min.  2. The method according to p. 1, characterized in that phosphoric acid, or phosphorus-containing sludge, or boiler milk, or complex lignosulfonate, or liquid glass with a base modulus of 2.5 to 3.0 are used as a binder.