Fluidized bed type of harmless chromium slag pyrolysis process

Abstract

The invention relates to a fluidized bed type of harmless chromium slag pyrolysis process. The process is characterized in that biomass and chromium slag into are respectively added into a high temperature fluidized bed pyrolysis furnace, wherein the biomass rapid melts and pyrolyses to release a lot of pyrolysis gas in the process, so as to reduce Cr (VI); at the same time pyrolysis carbon residue attaches to fluidization process the chromium slag surface to protect the reduced Cr (III) reduction in chromium residue from secondary oxidation, and the chromium slag conducts effectively catalytic cracking on be produced pyrolysis gas to avoid generation of a lot of high-pollution tar gas. Compared with the traditional pyrolysis technology, the technology greatly shortens the residence time, at the same time produces energy tail gas with high heat value, and avoids the disposal of the exhaust.

Description

technical field [0001] The invention is a fluidized bed type chromium slag pyrolysis harmless process. Through process control, the Cr(VI) in the chromium slag can be efficiently reduced, and the reaction time can be greatly shortened. At the same time, the tail gas can be used as energy, saving energy. While saving energy, it avoids exhaust gas treatment. The invention belongs to the technical field of environmental protection. Background technique [0002] Chromium slag is a by-product emitted during the production of dichromate. Because it contains water-soluble Cr(VI), it is extremely toxic. If it is stacked in the open air without treatment, it will cause varying degrees of pollution to groundwater sources, rivers or sea areas, and seriously endanger human health and the growth of animals and plants. [0003] Generally speaking, the current detoxification methods for chromium slag (i.e. changing highly toxic Cr(VI) to Cr(III)) are divided into two categories: wet deto...

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Problems solved by technology

However, this process has many defects. On the one hand, the process adopts the rotary kiln process, and the material stays in the kiln for a long time, so the processing efficiency is low.

On the other hand, since the process mixes organic matter and chromium slag in the low temperature area, during the process of the two moving to the high temperature area, the organic matter in the sludge will continuously produce tar gas and enter the tail gas along the air flow, and the tar gas contains a large amount of such as Carcinogens such as cycloaromatic hydrocarbons are easily discharged in the form of PM2.5 during the cooling process, which is extremely harmful, so secondary treatment is required for the exhaust gas

In addition, the tar gas produced by the organic matter in this process is diluted by the high-temperature gas flow, resulting in a decrease in the concentration of reducing gases in the gas flow, and the reduction atmosphere is not strong, which reduces the reduction efficiency of Cr(VI)

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