SU1673506A1 - Method of heat treatment of phosphorite pellets - Google Patents

Abstract

This invention relates to a process for preparing phosphate raw materials for phosphorus processing by electrothermal method. The aim of the invention is to provide the possibility of involving in the processing of phosphate raw materials with a total content of alkali metal oxides of more than 1.5% while maintaining the high performance of the heat treatment process. The method consists in drying the pellets, heating to the firing temperature, and from 1000 to 1200 ° C, heating is carried out at a speed of 15-30 degrees / min. 1 tab.

Description

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This invention relates to a process for preparing phosphate raw materials for phosphorus processing by the electrothermal method.

The purpose of the invention is to provide the possibility of involving in the processing of phosphate raw materials with a total content of alkali metal oxides of more than 1.5% while maintaining high productivity of the heat treatment process.

PRI me R 1, Raw phosphate pellets obtained from a slurry enrichment slurry with a particle size of 0.14-0 mm and containing 67% of the class 0.074-0 mm in an amount of 36 kg are loaded into a bowl imitating a conveyor kiln, on top of a bed of burned pellets. The pellets are dried and heated, and then the flow rate of natural gas and air is controlled so that the rate of temperature rise in the range of 1000-1200 ° C is 25 deg / min.

Then the pellets are subjected to recovery and cooling, after which a sample is taken for chemical analysis. The content (K20-N320) in the feedstock is 2 0%, in the pellets after heat treatment in the center 2.09%, at the periphery 0.8%.

R table presents comparative data on the specific productivity of the process depending on the heat treatment mode, as well as data on the prototype

As can be seen from the table, when the alkali metal content is more than 1.5% (1.6-2.8%) and the temperature rise rate is 15-30 degrees / min, the specific productivity of the roasting machine is at the level of the prototype (0.33 t / m. h) the content of alkali metals on the surface of the pellet is reduced to 0.56-0.58%, in the center 1.59%. In this mode of firing, an intensive formation of liquid-fluid VJ with

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phase and the completion of the decarbonization of alkali and alkaline-earth metals reduces the total partial pressure of gases from the center to the periphery

The absence of pressure from the center of the pellets to the periphery, associated with the completion of decarbonization, promotes the movement of the flowable melt inside the pellet, te in the colder zone. Therefore, a constant temperature gradient of the center of the pellet promotes the movement of the melt into the pellet - the surface that must be maintained from the beginning of the formation of an intense liquid-fluid melt. At lower values of the temperature rise rate (14 deg / min as in example 1), the alkali metal content over the surface almost the same as in the center of the pellet, which does not allow the pellets to be processed efficiently while reducing the productivity of the pellet.

At a higher speed (31 deg / min as in example 4), the effect of enriching the center of the pellets with alkali metals decreases (1.31% of the surface of the pellet 1 of 61% center).

At the rate of changing the temperature of the bob to 30 and less than 1b deg / min, it does not ensure the normal pregeneration of silica with i-ness and goes through the decarbonization process, but my liquid phase development is sufficient.

Involving in the processing of industrial products of suspension enrichment in the amount of 960 thousand tons / g significantly reduces the cost of raw materials for the production of pellets because replacing part of the conditioned phosphate flour with sump: penny enrichment and ore with a high content of alkali metals allows you to involve significant amounts of p C danate phosphate rock Janatas for the production of phosphorus

Claims (1)

Invention Formula The method of heat treatment of phosphate pellets including their drying is heated to the firing temperature of 1200 ° C and firing, characterized in that in order to ensure the possibility of involving in the processing of phosphate raw materials with a total content of alkali metal oxides more than 1.5% while maintaining a high performance of the heat treatment process, heating from 1000 up to 1200 ° C, 15-30 degrees / min