CN1298892C

CN1298892C - Aluminium electrolyzing inert anode of Fe base aluminium oxide composite material and its preparing method

Info

Publication number: CN1298892C
Application number: CNB031108636A
Authority: CN
Inventors: 石忠宁; 邱竹贤
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-01-14
Filing date: 2003-01-14
Publication date: 2007-02-07
Anticipated expiration: 2023-01-14
Also published as: CN1425803A

Abstract

The present invention relates to the field of fused salt electrolysis in non-ferrous metallurgy, which mainly provides an anode material for the electrolytic industry of aluminum, rare earth, magnesium, etc. and a preparation process thereof. The present invention is characterized in that single metal or alloy is mixed with metal oxides, and the anode material for aluminum electrolysis is prepared in the method of powder metallurgy, wherein the single metal or the alloy is composed of iron, nickel, cobalt, chromium, titanium, copper, silver or the alloy thereof, and the metal oxide is single aluminum oxide or the aluminum oxide and rare earth oxide; the contents of the raw materials of the anode material are 8 to 95 mass percent of the single metal or the alloy, 5 to 87 mass percent of the aluminum oxide and 0 to 5 mass percent of the rare earth oxide. The present invention has the main characteristics that an anode does not take part in an electrode reaction in using, the product from the anode is oxygen, and the currently used consumable carbon anode can be replaced; thereby, energy saving, environmental protection and the large benefits of investment for unit productivity can be realized, and the fast, efficient and environmental protecting development of the electrolytic industry of the aluminum in China can be realized.

Description

Aluminum electrolysis inert anode made of metal-based aluminum oxide composite material

1. The technical field is as follows:

the invention relates to the field of molten salt electrolysis in nonferrous metallurgy, and mainly develops an electrolytic industrial anode material such as aluminum, rare earth, magnesium and the like and a preparation method thereof.

2. Background art:

the current aluminum electrolysis industry uses the Hall-Heroult method, and the anodes are all carbon anodes (also called graphite anodes). During electrolysis, anode carbon is oxidized and consumed, and the electrode reaction is as follows: . And then, carrying out secondary reaction on the anode gas: more anode carbon is consumed and a large amount of toxic CO gas is generated. The theoretical consumption of carbon is 444 kilograms for each ton of aluminum produced, the actual consumption of aluminum factories is about 600 kilograms, and the anode cost accounts for about 17-22 percent of the aluminumproduction cost due to the fact that the consumption of high-quality carbon materials is larger and the price is increased.

The existing consumable carbon anode has the following defects:

(1) a large amount of high-quality coke and petroleum coke are consumed;

(2) emission of large amounts of greenhouse gases and toxic gases, e.g. CF₄、CF₆PNAH polycyclic aromatic hydrocarbons (produced during anode production), volatile organic compounds VOC, HF, SOx, COS and NOx;

(3) the anode replacement cost is high and the labor intensity is high;

(4) and the unit capacity has large one-time investment.

3. The technical scheme is as follows:

the invention provides an aluminum electrolysis inert anode made of a metal-based aluminum oxide composite material, and aims to solve the problems of consumption of anode carbon due to oxidation, pollution to production environment and the like in the production process of aluminum electrolysis.

The invention is realized by the following technical scheme:

an aluminum electrolysis inert anode made of a metal-based aluminum oxide composite material is characterized in that: the anode material is a composite material formed by the following single metals or alloys thereof, metal oxides and rare earth oxides; the single metal is selected from iron, nickel, cobalt, chromium, titanium, copper and silver; the metal oxide is aluminum oxide; the rare earth oxide is selected from cerium oxide, lanthanum oxide and praseodymium oxide.

The alumina is selected from α -Al₂O₃、β-Al₂O₃、γ-Al₂O₃、 δ-Al₂O₃、ε-Al₂O₃、η-Al₂O₃、ζ-Al₂O₃And (3) alumina.

The anode material comprises 8-95% of single metal or alloy by mass, 5-87% of aluminum oxide by mass and less than 5% of rare earth oxide by mass.

The invention is mainly characterized in that the anode does not participate in electrode reaction in the using process, the anode product is oxygen, and the invention also has the following advantages:

1. byproduct O while realizing green production₂Economic benefits can be generated;

2. the cell voltage can be greatly reduced by matching with the wettable cathode, and the energy-saving effect is realized.

Based on the key points and hot spots of the aluminum industry development in the world at present, the invention develops the successful iron, nickel, cobalt, chromium, titanium, copper and silver high-temperature alloy based aluminum oxide composite aluminum electrolysis inert anode on the basis of a large amount of experimental researches. Aims to replace the consumable carbon anode used at present and realize the huge benefits of energy saving, environmental protection and unit productivity investment. Promotes the rapid, efficient and environment-friendly development of the aluminum electrolysis industry in China.

4. The implementation mode is as follows:

the anode material is developed through the following steps and ways:

the corundum fired by the alumina has excellent corrosion resistance in electrolyte fused salt but is not conductive, and the invention is based on the corrosion resistance of the alumina corundum, adds the high-temperature alloy components with oxidation resistance and corrosion resistance, and is sintered in the sinteringtemperature range of the alumina to form the conductive corundum. The prepared anode material has excellent conductivity, is convenient to connect with a power supply, has wide material source, low price and low manufacturing cost, and is beneficial to industrial large-scale use.

The anode material is prepared by a cold pressing method comprising four steps of material preparation, material mixing, molding and sintering, and a hot pressing method comprising three steps of material preparation, material mixing and hot pressing molding.

Preparing materials: metal powder or metal alloy powder (Cu, Fe, Ni, Co, Ti or their alloy) is ball milled for 48 hours to reach 200 mesh granularity, and the ratio of ball to material to ethanol is 2: 1; and ball milling the alumina powder for 72 hours to ensure that the granularity reaches 5-45 mu, wherein the ratio of the ball to the material to the deionized water is 3: 1.5: 1.

Mixing materials: after drying, water or polyvinyl alcohol is used as a binder to be evenly mixed, and the mixture is placed for 20 hours.

Molding: comprises cold press molding and grouting molding, wherein the cold press molding condition is 200-500MPa at normal temperature, and the grouting molding is manufactured in a mold with a specific shape.

And (3) sintering: and naturally drying the sample prepared by cold pressing and grouting at normal temperature, sintering the sample for one to three hours in an inert atmosphere within the sintering temperature range, and then cooling the sample to room temperature along with the furnace temperature under the protection of the inert atmosphere.

When hot pressing direct molding is adopted, the hot pressing temperature is 1050-.

The following examples are presented to illustrate the effects of the present invention.

Taking 40 g of alumina powder and 60 g of alloy (Fe: Ni: Co is 4: 3: 2), preparing an anode according to the method, taking high-purity graphite as a cathode, and forming an electrolyte with the current density of the anode being 1.0 ampere per square centimeter and the molar ratio of 1.8 and the alumina concentration being 3.0 percent into NaF-AlF at 850 DEG C₃-NaCl-CaF-Al₂O₃For electrolysis applications of up to several tens of hours. During electrolysis, the cathode and the anode are vertically inserted into a graphite crucible with corundum lining, and the polar distance is 3.6 cm. The test result shows that the electrolytic process is flatThe cell voltage is stable, 4.5-4.9 volts, the anode corrosion rate in the aluminum electrolysis process is low, and the quality of an aluminum product reaches 98.6 percent. Solves the problem of product pollution caused by alloy components in the process of metal-based inert anode electrolysis.

The overall electrode reaction of the electrolytic process can be written as:

during electrolysis, a large amount of gas is generated around the anode, and O is released according to the structural components of the anode and the composition of the electrolyte₂. After the electrolysis is finished, the anodic corrosion degree is small, and the anodic oxidation corrosion exposed in the air is smaller.

Claims

1. An aluminum electrolysis inert anode made of a metal-based aluminum oxide composite material is characterized in that: the anode material is a composite material formed by the following single metals or alloys thereof, metal oxides and rare earth oxides; the single metal is selected from iron, nickel, cobalt, chromium, titanium, copper and silver; the metal oxide is aluminum oxide; the rare earth oxide is selected from cerium oxide, lanthanum oxide and praseodymium oxide.

2. The aluminum electrolysis inert anode made of the metal-based aluminum oxide composite material as claimed in claim 1, wherein the aluminum oxide is selected from α -Al₂O₃、β-Al₂O₃、γ-Al₂O₃、δ-Al₂O₃、ε-Al₂O₃、η-Al₂O₃、ζ-Al₂O₃And (3) alumina.

3. The metal-based alumina composite aluminum electrolysis inert anode of claim 1, wherein: the anode material comprises 8-95% of single metal or alloy by mass, 5-87% of aluminum oxide by mass and less than 5% of rare earth oxide by mass.