A system and process for producing cryolite with alkaline etching solution

Abstract

The invention relates to a system for producing cryolite from alkaline etching liquid. The system comprises an alkaline etching liquid generating system, an alkaline etching liquid collecting system,an alkaline etching liquid treating system and an alkaline etching liquid separating system. The alkaline etching liquid generating system comprises an alkaline etching groove, a fifth alkaline etching liquid retaining groove, a sixth alkaline etching liquid retaining groove, a spray groove, a fourth pump and a fifth pump; the alkaline etching liquid generating system is used for processing aluminum materials and generating the alkaline etching liquid; the alkaline etching liquid collecting system comprises an alkaline etching liquid recycling tank and a first pump; the alkaline etching liquidcolleting system is used for collecting the alkaline etching liquid; the alkaline etching liquid treating system comprises treatment tanks, a second pump and a hydrofluoric acid storage tank; the alkaline etching liquid treating system is used for carrying out chemical reaction on the alkaline etching liquid and producing the cryolite; the alkaline etching liquid separating system comprises a recycling tank and a centrifugal machine. The system has the advantages that aluminum ions in waste liquid of the alkaline etching liquid can be completely recycled to generate the cryolite by the system, wastewater can be recycled to be reused, and accordingly the system is free of waste residue and wastewater emission.

Description

technical field [0001] The invention relates to the technical field of aluminum processing, in particular to a system and process for producing cryolite with alkaline etching solution. Background technique [0002] Aluminum and aluminum alloys have the advantages of excellent processing performance, good corrosion resistance, beautiful surface, high recovery rate, etc., and have been widely used in construction, transportation, machinery, electric power and other industries. In recent years, the trend of expanding the application of aluminum by replacing steel with aluminum has become more obvious . The aluminum processing industry is a traditional industry, and it is a sunrise industry full of vitality. According to statistics, the per capita annual consumption of aluminum in developed countries in Europe and the United States is more than 32kg, while the per capita consumption in my country is only about 13kg, which is only about one-third of that in developed countries. ...

AI Technical Summary

Problems solved by technology

In recent years, the proportion of oxidized electrophoretic materials has decreased, but most aluminum factories still have more acidic wastewater than alkaline wastewater. The acidic and alkaline water are all mixed together for treatment. The mixed wastewater is acidic, and a large amount of caustic soda, lime, PAC, and PAM needs to be invested. generated a lot of waste

[0016] 2. Current status of aluminum industry waste slag treatment and utilization

At present, there are three main routes for resource utilization of aluminum ash: (1) recycle alumina and return it to electrolysis, and recycle chloride salt as a melting and casting refining agent. However, the main component in aluminum ash is α-Al2O3, which has poor activity, and its ionization requires Consumes more energy, causing cell voltage to rise

(2) Acid or alkali treatment to remove impurities, production of inorganic materials such as synthetic brown corundum, Sialon ceramics and refractory materials, production of water purification materials such as polyaluminum chloride and aluminum sulfate, and production of slagging desulfurizers for steelmaking, but due to The cost is higher than the existing ones, and industrial production cannot be realized

(3) Production of building materials or road construction materials, such as aluminate cement, calcium aluminate powder, clear water bricks, and road construction materials, etc., but the fluoride and chloride salts contained in them have an impact on performance, and the added value of the product is low, limiting practical application

This method is simple, but has the following disadvantages: first, it loses sulfuric acid, wastes aluminum ions, and the consumption of sulfuric acid reaches more than 60kg / t;

[0036] The traditional waste water and residue treatment methods have the following disadvantages: first, the waste water can be discharged after treatment, but the reuse rate of reclaimed water is low; second, the cost of waste water treatment is high, which increases the consumption of labor, chemicals, and power; third, a large amount of acid, alkali, and metal aluminum , chemicals and other useful resources are wasted; Fourth, the waste residue is hazardous waste, the disposal cost is high, and environmental protection tax must be paid

[0042] 3. There are problems in the treatment of waste water and residue in extrusion surface treatment

[0043] First, high water consumption, lack of mature water-saving technology, and low water reuse rate; second, online classification of wastewater has not become a pre-procedure, resulting in a large amount of waste residue; third, the comprehensive utilization of waste residue has little effect, and waste residue treatment Become a corporate burden and environmental risk

[0044] At present, there are three prominent contradictions and problems in the treatment of waste residues: First, the state implements the management of enterprise pollutant discharge permits to control the total amount of pollutants discharged by enterprises, but the actual amount of waste water and residues of enterprises is far greater than the allowable discharge amount; second, waste residues must be It is legally transferred to a qualified third party for disposal, but the disposal capacity is obviously insufficient to legally dispose of such a huge amount of waste residue; the third is to dispose of waste residue according to hazardous waste regulations, which has complicated procedures, low efficiency and high cost

[0045] To sum up, the current domestic aluminum processing industry waste water and slag treatment contradiction is prominent, comprehensive treatment is difficult, high cost, and low recycling rate, which not only causes a lot of waste of resources, but also seriously pollutes the environment

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