Process for comprehensively utilizing rare-earth ore leaching waste liquid and calcining waste heat in rare earth production

Abstract

The invention discloses a process for comprehensively utilizing rare-earth ore leaching waste liquid and calcining waste heat in rare earth production, which comprises the following steps of: treating the waste water discharged after dissolving rare-earth ores by acid by using lime, to form residue containing a large amount of calcium, iron and aluminum salts; and adding sulfuric acid with a mass percentage concentration of above 70 percent into the residue for curing to prepare an aluminum sulfate molten iron finishing agent containing calcium sulfate, wherein curing is realized by comprehensively utilizing the waste heat generated by rare earth calcination and smoke chamber waste heat of a boiler. By adopting the invention, the problem of higher cost of synthesizing the conventional inorganic polymeric flocculant aluminum ferric sulfate is solved, and the problems of large amount of residue generated by waste treatment, difficulty in treatment of the residue, low temperatures of calcining waste heat and boiler smoke chamber waste heat discharged during the rare earth production, and difficulty in comprehensive utilization in the traditional rare earth smelting process are solved; the aluminum ferric sulfate containing the calcium sulfate, with high economic benefit, is prepared on the basis of the original process, and the aluminum ferric sulfate can be used as the finishing agent in the subsequent sewage treatment; and the preparation process is simple, the economic benefit is obvious, and the process is easy to popularize.

Description

technical field [0001] The invention relates to a comprehensive utilization process of rare earth ore leaching waste liquid and rare earth production calcination waste heat. technical background [0002] The overall performance of ferric aluminum sulfate is better than that of polyferric sulfate (PFS) and polyaluminum sulfate (PAS). It has the advantages of fast settling speed of iron salt flocculant, large alum flower, and good fading effect of aluminum flocculant. It has the advantages of polyaluminum chloride ( The characteristics and characteristics of PAC) and iron salts overcome the difficulty of PAC in purifying water at low temperature and low turbidity. Therefore, its water purification effect is obviously better than that of general water purification products. [0003] The method commonly used at present to prepare aluminum iron sulfate: with ferrous sulfate, H 2 SO 4 , Al(OH) 3 etc. as raw materials, in the oxidizing agent H 2 o 2 Synthesis of polyaluminum ...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that precise process control is required, which brings certain difficulties to the operation, and the oxidant H 2 o 2 More expensive and therefore more expensive to prepare

[0004] In China, fly ash discharged from thermal power plants and pyrite slag from chemical plants are also used to synthesize polyaluminum ferric sulfate (PAFS) flocculants at relatively high temperatures. The raw materials used in this method are factory waste, so it has relatively high Good economic and environmental benefits, but the disadvantage of this method is that Fe in raw materials 2+ The content is relatively high, and it is often necessary to add an oxidant (such as MmO 2 ), and the process is cumbersome and the synthesis time is long, which is not conducive to industrial production

When only lime is used for treatment, the sedimentation speed is slow and the sewage treatment capacity is low. If conventional flocculants (such as polyaluminum chloride) are assisted, not only the cost is high, but the treatment effect is not very good

During the lime precipitation process, due to the large amount of residues produced, the residues are difficult to handle, thus causing greater environmental pressure on sewage treatment

The current method of treating residues is usually to squeeze them and transport them to other places for landfill. This method not only has high processing costs, but also produces calcium, iron and aluminum salts that are difficult to use economically.