Process for recovering white slime and tunnel type calcining kiln for the method

Abstract

The invention discloses a method for recovering white mud and a tunnel type calcinating kiln using the same. The method is to recover white mud by subjecting a great deal of white mud generated as a by-product in the production of pulp and paper enterprises to water filtration, mud regulation, brick making, car loading, calcination and kiln discharge and other processes and to calcine the white mud in the tunnel type calcinating kiln at a temperature of between 1, 050 and 1, 250 DEG C, which solves the problem of difficult recovery of white mud. The method has the advantages of simple process, energy conservation, high recovery and low cost.

Description

technical field [0001] The invention relates to a white mud recovery method and a tunnel type calciner used in the method. technical background [0002] At present, domestic pulp and paper companies are under the pressure of environmental protection, and at the same time, based on their own requirements for cost reduction, large and medium-sized factories are equipped with alkali recovery systems to deal with the black liquor produced in the pulping process. The black liquor is concentrated and burned. , free NaOH is converted to NaCO 3 , commonly known as "green liquor", the green liquor is converted into NaOH after lime causticization, and a large amount of solid by-products are produced during the lime causticization process ----- the main component is CaCO 3 , commonly known as "white mud". For every ton of NaOH produced, 1-1.3 tons of lime mud will be produced, and the amount of lime mud produced by a 50,000-ton pulp mill will be as high as 50,000-70,000 tons per year...

AI Technical Summary

Problems solved by technology

The white mud light calcium technology has been promoted to a certain extent due to low investment and relatively simple process. However, due to the limitation of the amount and quality of paper and light calcium carbonate, the white mud light calcium technology can only be used in some enterprises, such as Pulp and paper companies that produce cultural paper carry out partial recycling, while pulp and paper companies that produce industrial paper and cultural paper that require high paper strength and quality, it is difficult to promote the use of light calcium technology

The patent (ZL02108007.0) of the application date on March 22, 2002 "recycling method for lime mud and vertical lifting calciner for this method" proposes to use the vertical lifting calciner to calcinate and reclaim lime mud. This method combines lime mud and The fuel coal is directly mixed and calcined, resulting in a gradual decrease in the calcium oxide content in the lime, and a reduction in the number of lime mud recycling; secondly, the stacking height of this method is 2-3 meters, which requires higher strength of bricks, so the dryness of lime mud is also stricter. , it needs to be dried twice, and aggregate (limestone particles) needs to be added to the white mud to increase the strength of the white mud brick. The process is cumbersome and the operation is complicated, resulting in high cost of harvesting.

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