Study On Producing Carbon Anode For Aluminium By High-temperature Mould Pressing Electrolysis

Anode is called the heart of aluminum electrolysis cell, and its quality is directly influence by the operation conditions and techno-economic data of the aluminum electrolysis cell. The commercial operation show that the70%of cell malfunction is caused by low quality anode. Anode materials are carbon materials, at present the main anode preparation methods is vibration molding. To improve the density of the anode carbon block by changing ingredients and formulations is a main way to improve the quality of the carbon anode, but it is very difficult to use the traditional technology to improve the density and resistance of carbon anode,while using heat-molding technology to produce pre-baking carbon anode can improve the density of anode, which will help to improve the quality of pre-baked carbon anode.This paper is based on the researched of optimization of the heat-molding carbon anode formula, the processes of the heat-molding and the physical and chemical properties of the pre-baked anode carbon. The researches show that:This paper is based on four grade petroleum coke aggregate (include15-8mm coarse, medium-grained8-5mm, fine5-2mm and powdered materials<0.075mm) ingredient. When the tap density reaches the maximum, the optimal particle size ratio is15.3%coarse,20%of medium-grained, fine-grained18%, and46.7%of the powdered material.Determined the mixing method under laboratory conditions:melted coal pitch, put it aside for cooling mill, by the proportion of weighing, each weigh the amount of one test. And then mix materials with not heated it.To determine the method under the laboratory condition:pressure system; early on10MPa pressure, pressure once every10minutes, every time pressure10MPa, until reaching the set of temperature and pressure, then keeping the pressure5min; current system:the initial current is200A, then increase current50A every5min, adjust current after reach300A according to the set the temperature and pressure. The best stripping temperature is80℃. Only under this moulding temperature and pressure system can make green anode block with the density of1.66～1.69g/cm3and good apparent, difference of density in0.05g/cm3.The perfect process conditions to hot pressing compaction the anode carbon is in40Mpa in pressure briquette, moulding temperature of130℃, and the optimum pitch Content is15%. In these conditions we can get pre-baked anode with the volumetric density of1.61～1.63g/cm3, true density of2.09g/cm3,resistivity tends of57μΩ·m, air reaction scrape rate of72%, reaction of loss of26.1%,desquamated of1.9%,CO2reaction scrape rate of74.9%,loss of reactivity ratio of22.3%, desquamated of2.8%,and compressive strength of27Mpa. All these data are getting by pre-baked anode carbon.