1. Application of graphite anode

In an electrolyzer, the stage from which the current flows into the electrolyte is called the graphite anode plate. In the electrolysis industry, the anode is generally made into a plate shape, so it is called a graphite anode plate, which is widely used in electrolysis, wastewater treatment, industrial anti-corrosion equipment, or as special materials.

In the electrolysis industry, graphite anode plates have been used as anodes for more than 100 years, but metal anodes have been used in recent decades. 

Compared with other materials, graphite anode plate has the advantages of high-temperature resistance, good electrical and thermal conductivity, easy machining, good chemical stability, acid, and alkali corrosion resistance, and low ash content, so it can be used as the electrolysis of aqueous solution for preparation of chlorine and caustic sodium, and as the electrolysis of salt solution to produce alkali. Graphite anode plates can also be used as a conductive anode in the electroplating industry so that the electroplated products have the advantages of smoothness, fineness, wear resistance, corrosion resistance, high brightness, and not easy-to-change color.

2. Application of graphite cathode carbon block

Graphite cathode carbon block is a carbon block made of high-quality anthracite, coke, graphite, etc., which is used as the cathode of the aluminum electrolyzer. It is built on the bottom of the electrolyzer, also known as the bottom carbon block. The cathode carbon block plays the dual role of conducting electricity and forming the lining of the electrolyzer.

Aluminum electrolysis production requires the cathode carbon block to have the characteristics of high-temperature resistance, molten salt corrosion resistance, electrical conductivity, good thermal conductivity, high mechanical strength, good thermal shock resistance, and strong sodium corrosion resistance, which is conducive to energy-saving and electrolyzer life improvement in aluminum electrolysis production.

The types of cathode carbon blocks are divided into three categories: ordinary cathode carbon blocks, semi-graphite carbon blocks, and graphite carbon blocks according to the quality requirements of the product, the selected raw materials, and the adoption of process conditions.

Ordinary cathode carbon blocks use anthracite calcined at 1250-1350°C as the main raw material.

Semi-graphitic carbon blocks are divided into two types according to different production processes. One is to use high-quality and high-temperature electric calcined anthracite or much more graphite fragments or even all graphite fragments as aggregates, and the formed green products are only roasted (the roasting temperature does not exceed 1200 ° C) and will not enter the graphitization furnace for heat treatment, this kind of carbon block is called semi-graphitic carbon block. The other is to use more easily graphitized coke as the aggregate, and after the formed green product is roasted, it enters the graphitization furnace for heat treatment at a temperature of 1800-2000 ° C. This kind of carbon block is called a semi-graphitic (chemical) carbon block. The former has higher strength and hardness, while the latter has better electrical conductivity and overall effect.

Graphitic carbon block is made of easily graphitizable coke, and its graphitization treatment temperature should reach about 2500°C.

The difference between a semi-graphitic carbon block and a graphite carbon block lies in the degree of the orderly arrangement of the crystal lattice of the product, that is, the degree of graphitization. The degree of graphitization can be represented by the resistivity of the product. The lattice of graphitic carbon blocks is basically in a state of orderly arrangement, and the resistivity is less than 15 μΩ·m; the degree of graphitization of semi-graphitic carbon blocks is low or only partially graphitized, and the resistivity is 15-45 μΩ·m. In terms of technology, it is expressed as heat treatment temperature. The maximum heat treatment temperature of the semi-graphitic carbon block is about 2000 ℃, and the graphitization treatment temperature of the graphitic carbon block is 2500-2800 ℃. The resistivity of ordinary cathode carbon block is 50~60μΩ·m.

The graphitized cathode is a conductive material used in the cathode of aluminum electrolyzers, which represents the development direction of the electrolytic aluminum industry. With the technological progress and development of the electrolytic aluminum industry, the electrolyzer is developing towards a large capacity above 300KVA, and the requirements for cathode materials are higher. The main advantage of the graphitized cathode is that it can strengthen the current, improve the current efficiency, achieve the purpose of increasing production and energy saving, and make the electrolyzer run stably. The larger the electrolyzer type, the more obvious the effect of stable operation, and the more obvious the improvement of current efficiency. The unit production capacity of aluminum electrolyzer using graphitized cathodes is increased by 10-15%, and the electricity-saving per ton of aluminum is more than 600KWh. Graphitized cathode aluminum electrolyzer is one of the materials prioritized by the state in the electrolytic aluminum industry due to its obvious effect of energy saving, consumption reduction, and emission reduction.