Method for preparing sulphoaluminate cement by-product ammonia sulfate by partly converting phosphogypsum

Abstract

The invention discloses a method of partially converting phosphorous plaster to prepare side product ammonium sulfate of aluminum sulfate, which has the main steps of converting phosphorous plaster, filtering and separating converted substances, neutralizing converted liquid, concentrating, crystallizing and drying aluminum sulfate solution, drying filtrated cake and bauxite, blending and homogenizing raw material, calcining and cooling grog, modifying, grinding and homogenizing grog, processing calcination tail gas and the like. The mixed material satisfying materials required by the production of aluminum sulfate cement is achieved by partially converting the phosphorous plaster which does not need to be preprocessed. No limestone is required to be additionally added, the application range of the phosphorous plaster with high ferric and aluminum impurity contents is widened, the procedures and the converting equipment are simplified, ammonia consumption and operation difficulty are reduced, the cost is saved, the discharge of secondary polluting substances is eliminate, the heat and the carbon dioxide carried out by the calcination tail gas are recovered and utilized, and the energy consumption can be effectively reduced to further save the cost. In addition, the method does not have high requirements on the impurity content of the phosphorous plaster and has strong suitability on the raw material.

Description

technical field [0001] The invention relates to the technical field of preparation of sulphoaluminate cement, in particular to a method for making sulphoaluminate cement by partial conversion with phosphogypsum waste slag as the main raw material and simultaneously producing ammonium sulfate by-product. Background technique [0002] China has become a major producer of phosphate and compound fertilizers in the world. High-concentration phosphate and compound fertilizers account for more than 50% of the total output. The by-product phosphogypsum stockpile in the production process reaches hundreds of millions of tons, and the annual increase is about 50 million tons. Phosphogypsum The resource utilization of phosphorus has become an important issue for the sustainable development of the phosphorus chemical industry. [0003] Usually, phosphogypsum is in the form of powder, the appearance is generally off-white, gray-yellow, light green, dark gray and other colors, and the bul...

AI Technical Summary

Problems solved by technology

Its disadvantages are: ① The proportion of phosphogypsum in the raw material is 20-25%, and the insufficient calcium still needs to be added with limestone, and the amount of phosphogypsum consumed per ton of product only accounts for 20-25% of all raw materials

②The process adopts vertical kiln calcination, which has high energy consumption, the reducing atmosphere of calcination is not easy to control, the product quality is unstable, and the production cost is also high

[0007] Using phosphogypsum as raw material to convert ammonium sulfate through carbonized ammonia has many reports, mainly including: "Using Phosphogypsum to Prepare Ammonium Sulfate" ("Henan Chemical Industry" magazine, sponsor: Henan Chemical Industry Research Institute, 1997, 9th issue, P37-P38) the phosphogypsum that one article introduces makes fertilizer grade ammonium sulfate product through the conversion of carbonized ammonia water, and its shortcoming is: 1. Raw material phosphogypsum must be carefully selected to improve the quality of phosphogypsum entering the production system, in order to ensure higher Phosphogypsum conversion rate and product quality, thereby increasing the cost of treatment, and the utilization of phosphogypsum residue with high impurity content is limited

The phosphogypsum introduced in the article "Comprehensive Utilization of Phosphogypsum to Produce High Concentration NPK Compound Fertilizer Industrial Experiment Research" ("Phosphorus Design and Powder Engineering" magazine, sponsor: Design Institute of Nanhua Group, Issue 5, 2004, P7-P9) Ammonium sulfate solution is obtained through the conversion of carbonized ammonia water, and further metathesis is carried out with potassium chloride to obtain the intermediate products required for the production of NPK compound fertilizers. Phosphogypsum needs to be rinsed before entering the ammonium carbonate water conversion system, which increases the cost of phosphogypsum treatment, and the phosphogypsum washing water and solid impurities in the process produce secondary wastewater and waste residue

②This process produces calcium carbonate waste residue that needs to be reused

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