RU1787934C - Method of agglomerating phosphate stock - Google Patents

Abstract

Essence: raw materials - phosphate class 0-10 mm. Heating and firing in a rotary kiln with heat carrier gas. The temperature of the heating gas rises from 750 to 1200-1400 ° C at a speed of 35-50 deg / min. The yield of the conditioned product is 80%, the specific productivity is 0.152 t / m. 2 tab.

Description

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The invention relates to a technology for the thermal preparation of phosphate raw materials for the electrothermal production of yellow phosphorus and can be used in the pelletizing of phosphate-siliceous fines and in the production of building materials in a rotary kiln.

Closest to the technical nature of the proposed technical solution is a method of sintering phosphorite fines, including mixing it with a binder, which is used as a 35-75% suspension of phosphorus sludge, feeding the mixture into a rotary kiln for pelletizing and firing at a temperature of 1100-1300 ° C for 40-50 minutes.

The disadvantages of the prototype are the low productivity of the process and the yield of the conditioned product.

The aim of the proposed technical solution is to increase the productivity of the process and the yield of the conditioned product.

PRI me R 1. 1000 kg of phosphate rock fines fraction of 0-10 mm, containing 350 kg (35%) of pulverulent material of class 0-1. mm, moistened to a moisture content of 6.5% and fed into the loading zone of the rotary kiln, where it, moving through the kiln, is subjected to heat treatment, firing and pelletizing at gas temperatures of 1200-1400 ° C.

The firing process in a rotary kiln is carried out in the following mode:

- the temperature of the heat carrier gas with a temperature of 750 ° C is raised at a speed of 42.5 deg / min to the material softening temperature (about 1200 ° C),

- the duration of the process as a whole from loading to unloading is 35 minutes, and the partially fused phosphate material is held in the pelletizing zone

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furnaces with a temperature of 1200-1400 ° C for 2, 3 minutes.

The heat treatment mode of the material with a certain heating rate, 35-50 deg / min, is maintained by adjusting the supply of secondary air to dilute the combustion products.

 The conglomerate obtained during the pelletizing process is cooled and sorted. The yield of class 5-70 mm grade material is 98%, and the furnace capacity is 0.152 t / m3 / h.

A study of the effect of distinguishing features on indicators of technical effect is presented in Table 1.

An analysis of the data in Table 1 shows that the optimal rate of increase in the temperature of the heat carrier gas in the material firing zone is 35-50 deg / min. If the temperature of the coolant gas in the firing zone of the rotary kiln is increased at a rate of less than 35 deg / min, then the product yield and process productivity are reduced as a result of the large volume of uncomposed fines.

If the temperature of the coolant gas in the firing zone is increased at a speed of more than 50 deg / min, then there is also a decrease in product yield and process productivity due to the need to crush large pieces of conglomerate.

Over the years, the inventors of the claimed technical solution have carried out studies on the heat treatment of lumpy Karatau phosphorites. In the course of studies, it was found that the decarbonization roasting of Karatau phosphorites begins with the decomposition of dolomite at a temperature of 720 ° C.

Therefore, the zone with a material temperature of 720 ° C, provided by a heat-transfer gas with a temperature of 750 ° C, is accepted as the beginning of the firing zone in a rotary kiln.

The beginning of the decarbonization of Karatau phosphorites at temperatures above 700 ° C was also established by other studies, see M.V. Kireeva, T.V. Stratonova, L.G. Dmitrieva. - Differential thermal and thermogas-volumetric analyzes of phosphorites of various deposits.

In: Elemental Phosphorus and its Processing Products. Issue 19. -L .: Khimi, p. 11-16.

The authors found that maintaining the temperature of the heat carrier gas at 700 ° C at the beginning of the firing zone of the rotary kiln does not provide preparation of the material for reflow and pelletizing in the pelletizing zone, resulting in a decrease in the yield of conditioned feed due to the large amount of uncoated material.

Maintaining the temperature of the coolant gas in the firing zone of more than 750 ° C leads to overheating of the material in the pelletizing zone and an increase in the amount of liquid phase, which contributes to the formation of large pieces and deposits on the lining of the rotary kiln. In addition, with an increase in the firing zone, the pre-heating zone of the material is reduced and the heat loss increases due to an increase in the temperature of the exhaust gases.

Table 2 presents information on the technological mode and technical efficiency of the known and claimed processes for sintering phosphate raw materials.

Comparison of the efficiency of phosphate raw material agglomeration according to the claimed method with the known indicator that the claimed technical solution prevents the formation of large pieces of pelletized material, as a result of which the yield and productivity of the proposed process increases.

The expected economic effect of using the inventive process when producing 100 thousand tons of conglomerate in a rotary kiln is 209 thousand rubles.

Claims (1)

SUMMARY OF THE INVENTION A method for sintering a phosphate feedstock of class 0-10 mm in a rotary kiln, comprising loading it, heating with a heat carrier gas, calcining and pelletizing at 1200-1400 ° C, wherein, in order to increase the productivity of the process and yield a conditioned product , the temperature of the coolant gas in the firing zone is increased from 750 ° C at a speed of 35-50 deg / min. Table 1 table 2