Method for reclaiming lignin and alkali from boiling black liquor

A technology of lignin and black liquor, applied in chemical instruments and methods, lignin derivatives, alkali metal compounds, etc., can solve the problems of degradation products without removing carbohydrates, filtrate cannot be recycled, and alkali recovery cannot be realized, Achieve the effect of increased recycling profits, no secondary pollution, and significant economic benefits

Inactive Publication Date: 2008-04-09
CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among them, there are the following problems in the alkali recovery method of adding lime emulsion: 1. organically bound sodium cannot be converted into NaOH, and NaOH is not realized. 2 The circulation of S; ②The degradation products of carbohydrates are not removed from the black liquor, and the recovered filtrate cannot be recycled; ③The process generates more Ca 2 SO 4 Precipitation cannot be calcin

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] The masson pine kraft pulp cooking black liquor with a temperature of 80°C, a concentration of 10 Baume and a pH value of 14 is pumped into the 200m 3 In the acid analysis lignin pool, add 10% H at the outlet of the pipeline 2 SO 4 The solution adjusts the pH of the black liquor to 5.5, and after reacting for 20 minutes, the lignin in the black liquor precipitates out, and the lignin product is obtained after washing, centrifugal dehydration, and hot air drying. The clear liquid is pumped to 200m 3 In the alkali neutralization tank, add NaOH solution with a concentration of 60g / L at the outlet of the pipeline to adjust the pH of the black liquor to 7.5, and pump it to the dilute black liquor tank in the evaporation section after a reaction time of 10 minutes; use a pump to send the dilute black liquor to the 5th effect The mixed flow plate evaporator concentrates the black liquor to a solid content of 60%. The concentrated black liquor is sent to the jet combustion fu...

Embodiment 2

[0022] The eucalyptus kraft pulp cooking black liquor with a temperature of 75°C, a concentration of 11 Baume and a pH value of 14 is pumped into the 150m 3 In the acid analysis lignin pool, add 15% H at the outlet of the pipeline 2 SO 4 The solution adjusts the pH of the black liquor to 4.5, and after reacting for 25 minutes, the lignin in the black liquor precipitates out, and the lignin product is obtained after washing, dehydration by pressure filtration, and infrared drying. The clear liquid is pumped to 150m 3 In the alkali neutralization tank, add NaOH solution with a concentration of 100g / L at the outlet of the pipeline to adjust the pH of the black liquor to 7.2, and pump it to the dilute black liquor tank in the evaporation section after a reaction time of 15 minutes; use a pump to send the dilute black liquor to the 5th effect Mixed flow tube evaporator, concentrated black liquor with a solid content of 65%; the concentrated black liquor is sent to the jet combust...

Embodiment 3

[0024] Pump the poplar kraft pulp cooking black liquor with a temperature of 85°C, a concentration of 12 Baume, and a pH of 14 into the 180m 3 In the acid analysis lignin pool, add 20% H at the outlet of the pipeline 2 SO 4The solution adjusts the pH of the black liquor to 5.0, and after reacting for 20 minutes, the lignin in the black liquor precipitates out, and the lignin product is obtained after washing, centrifugal dehydration, and hot air drying. The clear liquid is pumped to 180m 3 In the alkali neutralization tank, add NaOH solution with a concentration of 150g / L at the outlet of the pipeline to adjust the pH of the black liquor to 7.1, and pump it to the dilute black liquor tank in the evaporation section after a reaction time of 16 minutes; use a pump to send the dilute black liquor to the 5th effect Mixed flow plate evaporator, the concentrated black liquor has a solid content of 68%; the concentrated black liquor is sent to the fluidized bed combustion furnace, ...

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PUM

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Abstract

The invention relates to a method for reclaiming lignin and alkali from steamed black liquor in chemical pulping. The invention adopts addition of H2SO4 solution into the black liquor to precipitate lignin thereof, and after separation, eylogen with high added value is obtained; then NaOH solution is added into the black liquor to adjust the pH value followed by procedures such as evaporation, combustion, causticization, etc. to reclaim alkali and heat energy. The added H2SO4 reacts with NaOH to produce Na2SO4, which can partially or completely substitute replenished mirabilite in the process of alkali reclamation and then transform into NaOH and Na2S for reuse as steaming drugs in production. The invention solves the problems that the combustion method for reclamation of alkali and heat energy from the black liquor does not rationally utilize the lignin resource thereof, and the alkali and the heat energy in the black liquor are not rationally reclaimed in the traditional acid extracting lignin process, as well as waster liquor is difficult to dispose further. The invention has prominent social, environmental and economic benefits; additionally, the method of the invention does not produce harmful substances and has no secondary pollution.

Description

Technical field: [0001] The invention relates to a method for recovering lignin and alkali from the cooking black liquor of alkaline chemical pulping. Background technique: [0002] The cooking waste liquid obtained from alkaline chemical pulping is called black liquor. The solids in black liquor include organic matter and inorganic matter. The organic matter is mainly the degradation products of lignin and carbohydrates, and the inorganic matter is mainly NaOH and Na 2 Transformation product of S. Among them, lignin accounts for 25% to 35% of the weight of black liquor solids, and 0.45 to 0.55 tons of lignin can be produced per ton of chemical pulp. Lignin is a high value-added chemical product, which has been widely used as surfactants, adhesives, flocculants, dispersants, concrete water reducers, activated carbon, dye additives, rubber additives, etc. The current market price is 2500-3000 yuan / ton; the inorganic substances in the black liquor can also be recovered by...

Claims

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Application Information

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IPC IPC(8): C01D1/00C01B17/22C07G1/00C02F9/04C08H7/00
Inventor 马乐凡
Owner CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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