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Process for recycling alkali in paper making black liquor

A black liquor and process technology, applied in the field of alkali recovery technology, can solve the problems of low alkali recovery rate, small degree of ionization, difficult to use on a large scale, etc., and achieve the effects of reducing production cost, low energy consumption, and moderate operating conditions

Inactive Publication Date: 2015-12-16
TAICANG WANGTAI PURIFYING EQUIP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Black liquor contains a large amount of suspended solids, organic pollutants and toxic substances. Direct discharge into water will cause serious pollution. Alkali recovery can not only greatly reduce the high-load pollution of black liquor, but also be used in the cooking stage of papermaking. Fundamentally eliminate the pollution of black liquor, but the alkali recovery process of the prior art generally adopts three methods of combustion causticization, direct alkali recovery and electrodialysis, and sulfides will be produced in the process of combustion causticization, which increases the treatment process of wastewater , secondly, the conditions of the hydrolysis reaction in the direct alkali recovery method are relatively harsh, and finally, the electrodialysis method needs to consume electric energy, and the degree of ionization is small, and the alkali recovery rate is low, so it is difficult to use on a large scale

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] A kind of alkali recovery process in papermaking black liquor, comprises the following steps:

[0016] (1) Add activated carbon to 2kg of wastewater for deodorization and detoxification, the ambient temperature for activated carbon adsorption is 18°C, and the adsorption time is 20 minutes;

[0017] (2) Pass 1kgCO? into the treated 2kg wastewater to obtain sodium bicarbonate solution;

[0018] (3) Cool down the sodium bicarbonate solution to 0°C, cool and crystallize to precipitate solid sodium bicarbonate;

[0019] (4) Burn 2kg of limestone to produce 2kg of calcium oxide, then add 2kg of water to prepare 2kg of calcium hydroxide solution, and collect 1kg of CO2 generated therein for use in step (2);

[0020] (5) Mix 2kg of calcium hydroxide solution and sodium bicarbonate aqueous solution to obtain caustic soda solution, realize alkali recovery, and collect 2kg of limestone produced therein for use in step (4).

Embodiment 2

[0022] A kind of alkali recovery process in papermaking black liquor, comprises the following steps:

[0023] (1) Add activated carbon to 2kg of wastewater for deodorization and detoxification, the ambient temperature for activated carbon adsorption is 22°C, and the adsorption time is 30 minutes;

[0024] (2) Pass 2kgCO2 into the treated 2kg waste water to obtain sodium bicarbonate solution;

[0025] (3) Cool down the sodium bicarbonate solution to 3°C, cool and crystallize to precipitate solid sodium bicarbonate;

[0026] (4) Burn 2kg of limestone to produce 2kg of calcium oxide, then add 2kg of water to prepare 2kg of calcium hydroxide solution, and collect 1kg of CO2 generated therein for use in step (2);

[0027] (5) Mix 2kg of calcium hydroxide solution and sodium bicarbonate aqueous solution to obtain caustic soda solution, realize alkali recovery, and collect 2kg of limestone produced therein for use in step (4).

Embodiment 3

[0029] A kind of alkali recovery process in papermaking black liquor, comprises the following steps:

[0030] (1) Add activated carbon to 2kg of wastewater for deodorization and detoxification, the ambient temperature for activated carbon adsorption is 25°C, and the adsorption time is 40 minutes;

[0031] (2) Pass 3kgCO? into the treated 2kg wastewater to obtain sodium bicarbonate solution;

[0032] (3) Cool down the sodium bicarbonate solution to 6°C, cool and crystallize to precipitate solid sodium bicarbonate;

[0033] (4) Burn 2kg of limestone to produce 2kg of calcium oxide, then add 2kg of water to prepare 2kg of calcium hydroxide solution, and collect 1kg of CO2 generated therein for use in step (2);

[0034] (5) Mix 2kg of calcium hydroxide solution and sodium bicarbonate aqueous solution to obtain caustic soda solution, realize alkali recovery, and collect 2kg of limestone produced therein for use in step (4).

[0035] The beneficial effects of the invention are: th...

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Abstract

The invention discloses a process for recycling alkali in paper making black liquor. The process includes the steps of firstly, adding activated carbon into waste water for deodorizing and detoxifying; secondly, feeding CO2 into the processed waste water to obtain sodium bicarbonate solution; thirdly, cooling and crystalizing to separate out solid sodium bicarbonate; fourthly, burning limestone to produce calcium oxide, and preparing calcium hydroxide solution; fifthly, mixing the calcium hydroxide solution with sodium bicarbonate aqueous solution to obtain caustic soda solution. The process has the advantages that the process is recyclable in material, mild in operation condition, low in energy consumption, and energy saving and environmental friendly, oxygen produced in the process can be used in the pulp oxidation process of a paper making process, and production cost is lowered greatly.

Description

technical field [0001] The invention relates to a papermaking process, in particular to an alkali recovery process in papermaking black liquor. Background technique [0002] The wastewater produced by the alkaline (caustic soda and sulfate) pulping process of the paper industry contains a large amount of lignin and is dark brown, so it is called black liquor. Black liquor contains a large amount of suspended solids, organic pollutants and toxic substances. Direct discharge into water will cause serious pollution. Alkali recovery can not only greatly reduce the high-load pollution of black liquor, but also be used in the cooking stage of papermaking. Fundamentally eliminate the pollution of black liquor, but the alkali recovery process of the prior art generally adopts three methods of combustion causticization, direct alkali recovery and electrodialysis, and sulfides will be produced in the process of combustion causticization, which increases the treatment process of wastew...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C11/04
CPCY02P40/40
Inventor 黄荣翠
Owner TAICANG WANGTAI PURIFYING EQUIP