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A method for recovering active lime from pulping and papermaking white mud

A technology of activated lime, pulping and papermaking, applied in lime production, etc., can solve the problems of insufficiently decomposed or decomposed lime, slow cooling speed, overburning, etc., and achieve lower calcination temperature, higher production efficiency, and faster heat transfer speed Effect

Active Publication Date: 2018-10-16
王桂林
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When flame calcination is used to decompose calcium carbonate, it is easy to appear "over-burning" or "under-burning", resulting in the product becoming a mixture of under-decomposed and decomposed lime or a mixture of decomposed and over-decomposed lime
When the rotary kiln calcination process is cooling, the cooling speed is slow

Method used

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  • A method for recovering active lime from pulping and papermaking white mud

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Experimental program
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Effect test

Embodiment 1

[0031] Depend on figure 1 As can be seen, a kind of pulping and papermaking lime mud reclaims the method for active lime, and it may further comprise the steps:

[0032] (1) Purification treatment: Purify the causticized green liquor to remove (SiO 2 , Fe 2 o 3 Plasma) impurities;

[0033] (2) Dehydration: The causticizing lime mud is forced to dehydrate through a filter to generate water-containing lime mud powder with a water content of ≤ 35% (the water content in this embodiment is 35%);

[0034] (3) Calcination and decomposition: start the high-temperature blower 3 at the outlet of the cyclone of the first-stage preheater 41 and the second-stage preheater 42 as a suspension power source, and use the gas produced by the gas generator or coal powder as fuel, Delivered to the hot blast furnace combustion device 19 through the fuel pipeline, the calcining and decomposing high-temperature hot air environment required by the calcining and decomposing furnace 7 is produced, a...

Embodiment 2

[0049] The water content of the water-containing lime mud powder in step (2) of this embodiment is 20%; the high temperature environment is maintained at 1100° C. in step (3).

[0050] The residual alkali content of the lime mud obtained by the step (1) of the present invention is ≤0.5%, the sulfur content is ≤0.1%, and the excess ash is ≤0.5% (in this embodiment, the residual alkali content is 0.35%, the sulfur content is 0.08%, and the excess ash is 0.3%); The pulverized coal described in step (3) is the sulfur-free coal used, the temperature of the calcination and decomposition high-temperature hot air environment is 850-900°C (900°C in this embodiment), and the high-temperature environment is 900°C-1100°C ( This embodiment is 1100 ℃), the air flow formed by the high temperature blower 3 is 4000-4500m 3 / t white mud powder (4500m in this example 3 / t)

[0051] The section wind speed of the dry separator 2 described in step (4) of the present invention is: 2.0 m / s~3.0m / s (...

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Abstract

The invention discloses a method for recovering active lime from a pulping and papermaking white mud. Pulverized coal or gas is used as a fuel, and the method is suitable for alkali recovery white mud generated in the pulping process of all fibrous raw materials including straw pulp, and the phenomenon of ring forming is prevented. The method is characterized by comprising the following steps: purifying, dehydrating, calcining, decomposing, cyclone-drying, primary pre-heating and the like; the materials are in suspension contact with hot air in equipment is utilized, so that the heat transfer area is increased, and the heat transfer is fast; the calcining temperature is reduced, the temperature of a decomposition reaction is only about 900 DEG C, and the fuel requirement is low; and besides, the production efficiency of calcination of the white mud is greatly improved, the operation of purifying to remove impurities is carried out before calcination to obtain the water-containing white mud with high content of calcium carbonate and low content of impurities, suspension calcination is adopted to avoid the phenomenon of ring forming, the application range of the process is wide, three-level cooling is adopted for cooling rapidly, and most of heat energy is recovered while the active lime is produced.

Description

technical field [0001] The invention relates to a recovery process of white mud produced in pulping and papermaking, in particular to a method for recovering active lime from pulping and papermaking white mud. Background technique [0002] Since the 1980s, some domestic pulp and paper enterprises have successively started to explore and develop the technology of alkali recovery white mud to prepare light calcium carbonate. Alkali recovery lime mud is solid waste produced in the alkali recovery workshop of pulp and paper making enterprises. Its main component is the precipitated calcium carbonate produced after the digestion and causticization reaction of green liquor and lime, which is strongly alkaline. The white mud and green mud slag in the causticizing stage of papermaking are the chemical reaction products of alkali recovery. They use soda ash (sodium carbonate) solution and lime as raw materials to cause causticizing reaction to generate sodium hydroxide (caustic soda)...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B2/10
CPCC04B2/10Y02P40/40
Inventor 王桂林
Owner 王桂林
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