RU2314354C2 - Method of chloro-ammonium deferrization of mineral raw materials - Google Patents

Abstract

FIELD: removal of inactive admixtures of ferric oxide contained in mineral raw materials.

SUBSTANCE: proposed method includes mixing of mineral raw material with ammonium salt and heating the mixture thus obtained. Used as ammonium salt is ammonium chloride which is mixed with raw material at ratio of 100-120% of stoichiometric amount required for interaction with ferric oxide. Burden thus obtained is heated to temperature of 320-350 C and is kept at this temperature for separation of volatile iron.

EFFECT: possibility of removal of iron without application of aqueous methods.

1 dwg, 5 ex

Description

The invention relates to the field of chemical technology of inorganic substances and can be used in cases where it is necessary to remove the main ballast impurity - iron oxide (III).

A known method of dissolving and leaching oxides of various metals by reacting them with hydrochloric acid during boiling. The disadvantage of this method is the inconvenience of handling hydrochloric acid due to the increased vapor pressure of hydrogen chloride over the solution and its high chemical aggressiveness [Akhmetov TG, Porfiryeva RT, Gaysin LG, Khatsrinov AI "Chemical technology of inorganic substances." In 2 book Prince 2, M .: "Higher school", 2002. S. 427].

A known method of removing the main ballast impurity - silicon oxide, using ammonium fluoride. The method involves mixing a pre-dispersed product with solid ammonium fluoride bifluoride and subsequent calcining the homogenized mixture in the temperature range of 100-500 ° C. When the gas phase is cooled, a solid product is released - desublimate, which is a mixture of silicofluoride and ammonium fluoride bifluoride. Desublimate is a raw material for producing fluoride compounds, including for the production of ammonium fluoride bifluoride, which can be recycled [RU 2226500].

A known method of processing nickel ores [AS No. 50401 from 01/31/1937, according to the application No. 178520 from 10/18/1937], selected as a prototype. The method consists in treating nickel ore with ammonium salts at a temperature not higher than the sublimation of ammonium salts, followed by leaching of a valuable component. The disadvantage of the prototype method is the need for leaching of a valuable component, i.e. introduction to the process of a stage requiring the use of water and related equipment associated with pumping liquid and filtering.

The task of the invention is to develop a new technological method for iron removal by using ammonium chloride without using aqueous methods of further processing.

The problem is achieved by mixing pre-crushed mineral raw materials with ammonium chloride and kept at a temperature of 320-350 ° C. The amount of ammonium chloride used is 100-120% of the stoichiometric. The reaction proceeds according to the following formula:

Fe ₂ O ₃ + 6NH ₄ Cl = 2FeCl ₃ + 6NH ₃ + 3H ₂ O

As a result of the reaction, iron chloride is obtained and gaseous ammonia and water are released. NH ₄ OH can be obtained from ammonia and water by condensation in a liquid adsorber.

The advantage of using ammonium chloride over ammonium fluoride is its selective effect on metal oxides. Ammonium chloride does not react with silicon oxide, which often forms the basis of ore mineral raw materials. Unlike hydrochloric acid, ammonium chloride under normal conditions is a non-aggressive and non-toxic substance, i.e. It does not create increased safety requirements. Ammonium chloride can be regenerated and returned to the process. Under the action of ammonia, previously condensed from the exhaust gases, on a solution of a metal chloride, ammonium chloride and metal hydroxide are formed again by the reaction:

FeCl ₃ + 3NH ₄ OH = Fe (OH) ₃ + 3NH ₄ Cl

In general, the process of chloroammonium deferrization of mineral raw materials can be represented by the scheme shown in the drawing.

Example 1

Mineral raw materials (copper slag), containing iron oxide in an amount of 10 g and ammonium chloride in an amount of 24 g, were mixed in porcelain dishes and heated to a temperature of 300 ° C. Maintained for 0.5 hours. The resulting mass was a mixture containing a highly soluble compound of iron chloride formed from iron oxide. The mixture was heated to a temperature of 350 ° C, there was a sublimation separation of iron chloride - iron removal of the raw material. The iron trichloride thus separated was dissolved in water, ammonia water was added to the solution. After precipitation with ammonia from an iron hydroxide solution and separation by filtration, the remaining solution is ammonium chloride, which after evaporation can again be used to decompose a new batch of iron oxide. The initial iron content in terms of oxide in the feedstock is 56%; in the residue after chlorination, the iron content did not exceed 1%.

Example 2

It differs from Example 1 in that the reaction is carried out under isochoric conditions (in an autoclave) at a temperature of 350 ° C. This reduces the loss of ammonium chloride due to evaporation and desublimation and increases the speed of the process. The initial iron content in terms of oxide in the feedstock is 56%; in the residue after chlorination, the iron content did not exceed 1%.

Example 3

It differs from Example 1 in that the reaction is carried out with a deficiency of ammonium chloride in an amount of 19.5 g, which prevents contamination of iron trichloride with ammonium chloride, and after the reaction is completed, the mixture is heated to 350 ° C. The resulting iron trichloride is sublimated at a temperature above 303 ° C and is separated from non-volatile chlorides. The initial iron content in terms of oxide in the feedstock is 56%; in the residue after chlorination, the iron content did not exceed 1%.

Example 4

It differs from Example 1 in that hematite was used as a mineral raw material. The initial iron content in terms of oxide in the feedstock is 98%, in the residue after chlorination, the iron content did not exceed 1%.

Example 5

It differs from Example 1 in that slag formed as a result of coal combustion was used as a mineral raw material. The initial iron content in terms of oxide in the feedstock is 12%; in the residue after chlorination, the iron content does not exceed 1%.

Claims (1)

A method of chloroammonium deironization of mineral raw materials, comprising mixing the raw material with an ammonium salt and heating, characterized in that ammonium chloride is used as the ammonium salt, which is mixed with the raw material in proportions of 100-120% of the stoichiometric amount required for interaction with iron oxide, the resulting mixture heated to a temperature of 320-350 ° C and maintained at this temperature to separate volatile iron trichloride.