Method for producing phosphoric acid from phosphate ore by displacement method

Abstract

A method for producing phosphoric acid through a phosphate ore displacement method comprises the following steps: adding silicon dioxide and phosphate rock powder into an eddy kiln to carry out a high-temperature melting displacement reaction so as to displace P2O5 gas; obtaining an industrial-grade or food-grade phosphoric acid product through hydration, absorption, refining and purification of the displaced P205 gas; and adding alkali metal oxides or salts of kalium and sodium into melted slag to obtain a slag wool product through blowing and drawing. Compared with the prior kiln method phosphoric acid process, the method omits the reduction of phosphate ore, the oxidization reaction of phosphorus and the processes and equipment for the ball forming and drying of ore charge, and saves carbon for reduction. The method saves investment on equipment by about 60 percent, reduces furnace gas dust by 90 percent, and improves the unit kiln volume and the productivity in the unit time by more than 50 times and the reaction speed by more than 20 times. The method is characterized by simplified flow, simple and feasible operation and control, reliability and stability. During the technical process, no waste residue or water is produced and discharged; and the discharged end gas basically has no impact on the atmosphere. The method is suitable for phosphoric acid manufacturers with an annual output of 1,000 to 800,000 tons industrial grade phosphoric acid.

Description

Technical field [0001] The invention relates to a method for replacing P in phosphate rock with silicon dioxide in a high-temperature molten state. 2 o 5 And a chemical process method for producing phosphoric acid. Background technique [0002] At present, the well-known kiln-process phosphoric acid production process represented by Patent No. 931114470 is to mix phosphate rock powder, carbon powder (coke powder or coal powder), and silica powder in a certain proportion, mix them, and form them into balls (or molding ), after drying, use a rotary kiln for reduction, oxidation and calcination reactions. Materials are fed into the kiln from the high end of the rotary kiln, coal powder and air are sprayed into the low end to heat, and solid slag is discharged, and the furnace gas is discharged from the high end of the kiln and introduced into the hydration absorption device for hydration reaction to obtain phosphoric acid. The reaction formula is Ca 3 (PO 4 ) 2 +5C+3SiO ...

AI Technical Summary

Problems solved by technology

The reaction formula is Ca 3 (PO 4 ) 2 +5C+3SiO 2 →3CaSiO 3 +P 2 +5CO,P 2 +2 1 / 2 o 2 →P 2 o 5 , P 2 o 5 +3H 2 O→2H 3 PO 4 , the existing kiln phosphoric acid production process mainly has long reaction time, low phosphorus reduction rate, long process, large amount of dust in furnace gas, and strict requirements on reaction temperature (the reaction cannot be carried out if the temperature is low, and the material will melt and adhere to the kiln wall if the temperature is high The formation of rings makes the rotary kiln unable to operate and the materials cannot be added), the equipment investment is large, the front and rear chambers of the kiln are difficult to seal, and the lack of reaction gas in the kiln is affected

So far, there is no kiln phosphoric acid production device in China that can operate continuously and stably for a long time, which hinders the industrial application of the existing kiln phosphoric acid process technology for many years.

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