Method and system for preparing alternative fuel by using aluminum electrolysis cell overhaul slag

Abstract

The invention belongs to the technical field of overhaul slag treatment, and discloses a method for preparing alternative fuel by utilizing aluminum electrolysis cell overhaul slag. The method specifically comprises the following steps of: S1, crushing the overhaul slag into small particles with the particle size of less than 15mm; and S2, proportioning a carbon-based additive and the small particles, and conveying the mixture into a tube mill for modified grinding to obtain a modified ground material. According to the method and the system for the method, the crushed small particles and the carbon-based additive are mixed according to the proportion and then the mixture is subjected to modified grinding; the carbon-based additive serves as a grinding-assisting combustion improver, so that the unit energy consumption is effectively reduced by 20% or above; and compared with the indexes of the original overhaul slag, the comprehensive heat value of the mixed material powder obtained after modified grinding is increased to 4000 kcal / kg or above; and meanwhile, the volatile matter of the powder is increased to 5-10%; due to the addition of the carbon-based additive, the ignition point of the powder is reduced by about 100 DEG C, and the combustion performance is improved.

Description

technical field [0001] The invention relates to the technical field of processing slag from overhaul of an aluminum electrolytic cell, and more specifically, relates to a method and a system for preparing a substitute fuel by using slag from overhaul of an aluminum electrolytic cell. Background technique [0002] In recent years, my country's electrolytic aluminum industry has developed rapidly. From 2017 to 2020, the output will reach more than 35 million tons, accounting for more than 55% of the world's total output. of high attention. Overhaul slag is a typical harmful solid waste discharged in the electrolytic aluminum production process. On average, every ton of electrolytic aluminum produced will produce 20-30kg of overhaul slag. The overhaul slag of aluminum electrolytic cells mainly includes cathode carbon blocks, refractory bricks, paste, and insulation bricks. , anti-seepage castables, refractory mortar and insulation boards, etc., due to the erosion of the electro...

AI Technical Summary

Problems solved by technology

[0004] At present, the treatment technology of electrolytic aluminum overhaul slag can be divided into safe landfill, wet treatment and pyrolysis, etc. Safe landfill occupies land resources and has not realized the reduction and recycling of overhaul slag in essence. The United States and other developed countries have ordered Landfill is prohibited, so it is not recommended to use; wet treatment is the research and development focus of overhaul slag disposal in recent years, including flotation technology and chemical leaching technology, etc. Wet treatment can separate electrolyte and carbon in overhaul slag, and the degree of resource utilization is high , but wet treatment needs to consider the purity of separated substances, wastewater treatment and other issues. The incineration process realizes solidification or disposal of harmful substances such as cyanide fluoride. As the current mainstream disposal method, the process is relatively simple, but there are still many problems restricting the development of the industry:

[0005] (1) The overall pretreatment is difficult and energy-consuming

Overhaul slag has high hardness and strong wear resistance. This is because castables and anti-seepage materials account for about 50% of the overhaul slag, especially high-strength castables such as silicon nitride combined with silicon carbide bricks, Mohs hardness is even higher. Reach 8-9 or more, so the existing overhaul slag pretreatment process generally has the problems of high energy consumption of the mill and large equipment loss

[0006] (2) The resource utilization rate is low, and the large-scale alternative fuel technology is immature

The cathode carbon block accounts for about 30-50% of the overhaul slag, but its carbon is mainly graphite crystal ordered structure, low volatile matter, high ignition point, poor combustion performance, and low replacement rate when directly used as an alternative fuel

[0007] (3) The application is limited

At present, the disposal of overhaul slag has not formed a resource alternative fuel, and the disposal idea is mainly to reduce the amount, and the heat value recovery and utilization of its heat value have not been realized at the same time.

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