CN1563500A

CN1563500A - Method for improving capability of electrolyte in technique of electrolytic aluminium

Info

Publication number: CN1563500A
Application number: CN 200410034421
Authority: CN
Inventors: 秦军; 陈志明; 吴彦宁; 严晓斌
Original assignee: QINYI IND GROUP CO Ltd NINGXIA
Current assignee: QINYI IND GROUP CO Ltd NINGXIA
Priority date: 2004-04-08
Filing date: 2004-04-08
Publication date: 2005-01-12
Anticipated expiration: 2024-04-08
Also published as: CN1295381C

Abstract

This invention relates to a method for improving electrolyte performance in the technology of electrolyzing Al which adds weight percentage of 1-10% NaCl in the electrolyte to effectively change the composition of Al electrolyte, improving its chemical and physical performance to reduce its melting point and reduce the electrolyzing temperature by 20deg.C and increase its conductivity and current efficiency over 1%.

Description

Method for improving electrolyte performance in electrolytic aluminum process

Technical Field

The invention relates to the field of metal smelting, in particular to a method for improving electrolyte performance in an electrolytic aluminum process.

Background

Until now, the aluminum electrolysis is realized by adopting a cryolite fused salt electrolysis method, namely, aluminum oxide is dissolved in a cryolite melt, aluminum is separated out at a cathode under the action of direct current, oxygen is separated out at an anode, and the oxygen reacts with carbon to generate carbon dioxide and carbon monoxide gas which are discharged out; technologists of aluminum electrolysis are always looking for an electrolyte with a lower melting point and better electrical conductivity, thereby improving current efficiency and reducing power consumption. The electrolyte produced by the prior aluminum electrolysis is alumina cryolite melt, and because of the introduction of raw materials, 2 to 4 percent of CaF is still contained in the electrolyte₂Some enterprises add 2.5-6% MgF to the electrolyte₂To lower the electrolysis temperature and improve the current efficiency, individual enterprises add Li to the electrolyte₂CO₃Then LiF is generated, so that the electrolysis temperature is reduced, the conductivity of the electrolyte is improved, the current efficiency is improved, and the power consumption is reduced, but MgF₂The addition of the electrolyte increases the specific resistance of the electrolyte while reducing the temperature, and has advantages and disadvantages for production; li₂CO₃The addition of (2) has good effect on electrolytic production, but the price is very high (about 28000 yuan/t), and the economic benefit is very little although the addition has good effect after the use.

Disclosure of Invention

The object of the present invention is to provide a method for improving the performance of an electrolyte in an electrolytic aluminum process by using a cheap, readily available metal salt.

The purpose of the invention is realized according to the following scheme: the method for improving the performance of the electrolyte in the electrolytic aluminum process is to add 1 to 10 weight percent of sodium chloride into the existing electrolyte to change the performance of the electrolyte;

the method for adding the sodium chloridecomprises the steps of heating and dehydrating the sodium chloride, mixing the sodium chloride with the alumina, and adding the electrolyte along with the charging material produced by electrolysis;

the method for adding the sodium chloride can also be that the sodium chloride is heated, dehydrated and ground, and then is mixed into the anode paste or the anode block according to a certain proportion and enters the electrolyte along with the consumption of the anode paste or the anode block.

The invention effectively changes the components of the aluminum electrolysis electrolyte, improves the physical and chemical properties of the electrolyte, reduces the melting point of the electrolyte, reduces the electrolysis temperature by about 20 ℃, improves the conductivity of the electrolyte, improves the current efficiency by more than 1 percent, increases the yield by more than 308 tons, reduces the power consumption by 185KWH/tAl, and can possibly generate electricity by theoretical analysis The electrolyte component is destroyed, and through tests, the reaction is not generated in the production practice, and the electrolyte component is stable, particularly the molecular ratio is stable; in addition, NaCl produces a fragmentation reaction due to the addition of NaCl: h₂O+2NaCl＝2HCl+Na₂The dissolution of O, HCl in water is a strong acid which may cause corrosion to equipment and buildingsFunction of the channelAfter the practice of the last year, all equipment and buildings are not corroded.

Detailed Description

The aim of adding NaCl to the industrial aluminum electrolyte is based on that the cryolite melt is adopted in the current aluminum electrolyte, when the ratio of the number of sodium fluoride to aluminum fluoride molecules (molecular ratio) of the cryolite melt is equal to 3, the melting point of the cryolite melt is about 1000 ℃, the melting point is correspondingly reduced along with the reduction of the molecular ratio, but when the molecular ratio is reduced to about 2.2, the volatilization loss is very large, the melting point is not low, the electrolysis temperature is about 950-. In order to reduce the melting point of the electrolyte, the conductivity of the electrolyte is improved, so that the electrolysis temperature and the specific resistance of the electrolyte are reduced, the dissolution loss of precipitated aluminum is reduced, and the current efficiency is improved; thereby reducing the voltage drop of the electrolyte and reducing the power consumption. Through repeated tests and tests, 1-10% of NaCl is added into the cryolite melt, so that the melting point of electrolyte can be well reduced, the electrolysis temperature is reduced, and the current efficiency is improved; can well reduce the specific resistance of the electrolyte, reduce the voltage and reduce the power consumption.

NaCl is first heated to dewater and then mixed with alumina, and the electrolyte is added together with the material produced in electrolysis or the NaCl is first heated to dewater and then ground to produce NaCl, which is then mixed into anode paste or anode block in certain proportion and fed into the electrolyte with the consumption of the anode paste or anode block. NaCl is cheap and low in investment, and can obtain better economic benefit.

Claims

1. A method for improving electrolyte performance in an electrolytic aluminum process is characterized in that 1-10 wt% of sodium chloride is added into the existing electrolyte.

2. The method of claim 1, wherein the sodium chloride is added by heating the sodium chloride to dehydrate it, mixing it with the alumina, and adding the electrolyte along with the feed produced by electrolysis.

3. The method of claim 1 wherein the sodium chloride is added by heating to dehydrate the sodium chloride, grinding, blending into the anode paste or block in a proportion that will enter the electrolyte as the anode paste or block is consumed.