Method for producing ammonium sulfur and potassium-calcium-silicon fertilizer by using phosphogypsum

Abstract

The invention discloses a method for producing ammonium sulfur and potassium-calcium-silicon fertilizer by using phosphogypsum. The method comprises the followings steps of: adding solution of ammonium carbonate and dried phosphogypsum into a reaction kettle, and performing solid-liquid separation of the obtained pulp by a filter press after reaction; adjusting a pH value of filtrate to 5.6 to 6.0, performing concentration and crystallization of the filtrate and drying the crystals to obtain the fertilizer-graded ammonium sulfate products; washing filter cakes by water, putting the filter cakes in drying equipment, introducing tail gas in a roller kiln furnace to dry the materials, performing heat-exchange drying of the materials in the drying equipment, and using the dried filter cakes a raw material for producing the potassium-calcium-silicon fertilizer; and drying and grinding potassium feldspar and the phosphogypsum, mixing the powder of the potassium feldspar and the phosphogypsum and the dried filter cakes, putting the mixture in a ball mill, putting the mixture in the drying equipment for drying, continuously putting the mixture in the roller kiln furnace for calcining, performing a solid-phase reaction, cooling the reaction products, and dry-grinding and granulating the cooled reaction products to obtain the potassium-calcium-silicon fertilizer, wherein the tail gas in the roller kiln furnace enters the drying equipment to perform the heat-exchange drying of the materials. The method has the advantages of simple process, low raw material cost and low energy consumption.

Description

technical field [0001] The invention relates to the comprehensive utilization of industrial solid waste and the production of agricultural chemical fertilizers, in particular to a method for producing ammonium sulfate and potassium calcium silicon fertilizer by using solid waste phosphogypsum, insoluble mineral potassium feldspar and ammonium bicarbonate as raw materials. Background technique [0002] Phosphogypsum is a by-product discharged during the production of wet-process phosphoric acid, and about 4-5 tons of phosphogypsum are produced for every ton of phosphoric acid produced. At present, the annual discharge of phosphogypsum in the world is more than 150 million tons. The annual discharge of phosphogypsum by my country's phosphorus chemical industry is about 50 million tons, accounting for more than 70% of industrial by-product gypsum, and it is still growing at a rate of 15% per year. At present, the accumulated storage of phosphogypsum in China exceeds 100 million ...

AI Technical Summary

Problems solved by technology

For example, the patent "A Method for Producing Ammonium Sulfate Using Phosphogypsum as a Raw Material" with the publication number CN101269823A adds unpurified phosphogypsum to an activator and matures it for 2-8 days before performing a conversion reaction, which solves the problem of increasing the cost of phosphogypsum purification. problem, but there is no detailed and economical plan for the treatment of by-product calcium carbonate; the patent "Method for Co-producing Ammonium Sulfate and Calcium Carbonate Using Phosphogypsum" with the publication number CN101492178A has carried out detailed modification treatment of calcium carbonate Elaborate, and then improve its utilization value, but the follow-up treatment process is extended, and the phosphogypsum that needs to be purified is still used, so the economy is also greatly reduced; the patent with the publication number of CN101481222A "Partial conversion of phosphogypsum to produce sulphoaluminate cement The method of producing ammonium sulfate as a by-product is very ingenious to wash and dry the filter cake containing calcium carbonate directly as the raw material for cement production, and the phosphogypsum does not need pretreatment, but the process of this invention is lengthy, the equipment is many, and the one-time investment high cost

At present, there is no report on the production process of ammonium sulfate and potassium calcium silicon fertilizer using phosphogypsum and insoluble mineral potassium feldspar as main raw materials