Recycling system and method for recycling agricultural compound fertilizer from polishing liquid for reducing slag in aluminum industry

Abstract

A recovery system and method for recovering an agricultural compound fertilizer from a polishing solution for reducing slag in the aluminum industry are provided. The system comprises a polishing solution wastewater intercepting unit, a polishing solution wastewater collecting unit, an aluminum phosphate recovery unit and an N-P compound fertilizer recovery unit. In the polishing solution wastewater intercepting unit, a 1# polishing tank, a 2# no-flow water washing intercepting tank, a 3# no-flow water washing intercepting tank and a 4# high-pressure spraying tank are arranged in reverse series. One end of a 1# cooling pipe is externally connected with the tap water, and the other end extends from the into the 2# no-flow water washing intercepting tank to the 3# no-flow water washing intercepting tank sequentially. The polishing solution wastewater collecting unit includes a pump 2, a pump 1 and a reaction tank. The aluminum phosphate recovery unit includes a pump 5, a cooling subsystem, a liquid ammonia tank and a filter press. The N-P compound fertilizer recovery unit comprises a recovery tank, a pump 7, a filter and a pump 6. By means of the system and method, aluminum in the polishing waste liquid can be converted into aluminum phosphate and sulfuric acid, and phosphoric acid and nitric acid can be converted into a liquid N-P composite fertilizer.

Description

technical field [0001] The invention relates to the technical field of aluminum processing, in particular to a recovery system and method for recovering agricultural compound fertilizer from a polishing solution for reducing slag in the aluminum industry. 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 abo...

AI Technical Summary

Problems solved by technology

[0010] 2.1. Extrusion mold waste liquid waste water waste residue

[0018] 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) Recycling alumina and returning it to electrolysis, and recycling chloride salt as a melting and casting refining agent, but the main component of aluminum ash is α-Al 2 o 3 , the activity is poor, and it takes more energy to ionize it, resulting in an increase in the cell voltage

(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;

The recovery of hexavalent chromium ions is still a difficult problem, and it is impossible to realize online recovery of chromium-containing agents

However, the evaporation process of trapped triacids produces a large amount of smoke, pollutes the environment, and costs a lot; the energy consumption of the triacidic evaporation process is huge, and the cost cannot be underestimated; the evaporation container corrodes too quickly and needs to be replaced every two years, which requires too much investment

In the actual operation of tri-acid recovery, there are problems such as large pollution, high energy consumption, low efficiency, and high cost.

[0045] To sum up, the traditional wastewater treatment process has the following deficiencies: first, the waste water can reach the discharge standard after treatment, but the reuse rate of reclaimed water is low; Useful resources such as acid and alkali, metal aluminum, and chemicals are wasted; fourth, the waste residue is hazardous waste, and the disposal cost is high, and environmental protection tax must be paid

[0053] 3. There are problems in the treatment of waste water and residue in extrusion surface treatment

[0054] 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

[0055] 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

[0056] 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

Images