CN1116128C

CN1116128C - Comprehensive rice husk utilizing method

Info

Publication number: CN1116128C
Application number: CN 01119431
Authority: CN
Inventors: 王子忱; 郭玉鹏; 宋利珠; 赵纯
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2001-05-25
Filing date: 2001-05-25
Publication date: 2003-07-30
Anticipated expiration: 2021-05-25
Also published as: CN1318437A

Abstract

The present invention relates to a comprehensive rice hull utilizing method. Submicron C/SiO2, nanometer silicon dioxide and active carbon with superhigh specific surface area can be prepared by using rice hulls as raw materials, and simultaneously, nanometer calcium carbonate as a byproduct can be obtained; thereby, materiel energy sources are fully utilized in the preparing process. C/SiO2 has favorable reinforcing action, and the nanometer SiO2 has high purity and good quality, and can be widely used for industry, such as rubber, plastic, paper manufacture, paint, etc. The method has the advantages of simple process, convenient preparation, reasonable source utilization, high added value of products, and obvious economical and social benefits.

Description

A kind of method of comprehensive utilization of rice husk

Technical field:

The present invention relates to a kind of method of comprehensive utilization of rice husk, particularly relate to a kind of with rice husk production submicron order C/SiO ₂Composite, production nanoscale SiO ₂, prepare that cleaning solution in active carbon with superhigh specific surface area and this process is handled, the method for the rice husk combustion heat and vent gas treatment.

Background technology:

China produces about 200,000,000 tons of paddy per year, is converted to about 40,000,000 tons of rice husk, accounts for more than 30% of Gross World Product, ranks first in the world, and calculate by theory, and annual China is single just can to extract about 8,000,000 tons of high-purity SiO in rice husk ₂It's a pity that the rice husk resource all is not fully utilized at present, has wasted as agricultural waste.China nineteen ninety-five patent CN1 has illustrated in 110,957 and has used rice husk to get process of active carbon as raw material by the gas activation legal system.In patent CN86104705, introduce the method that burning prepares amorphous silica, and had some to produce the method for silica, silicon tetrachloride and silicon nitride by rice husk in the early 1990s.All there are shortcomings such as air pollution is serious, product purity is low in these methods, and especially to the processing of the rice husk combustion heat, tail gas, the comprehensive utilization that reaches production high added value, environment protection significance product is not reported.

Summary of the invention:

Purpose of the present invention just provides that a kind of production technology is simple, low price, not only can produce submicron order C/SiO ₂Composite and nanoscale SiO ₂Deng product, and can significantly reduce to pollute, the product purity height, increase the rice husk comprehensive utilization method of economic benefit and social benefit greatly.

The method of comprehensive utilization of rice husk involved in the present invention comprises following four steps: (1) produces submicron order C/SiO ₂Composite; (2) produce nanoscale SiO ₂(3) processing of cleaning solution in the preparation active carbon with superhigh specific surface area process; (4) processing of the rice husk combustion heat and tail gas.

The present invention carries out charing with the rice husk secluding air, and carbonization temperature is 300 ℃～500 ℃, and the time is 30～120 minutes, prepares submicron order C/SiO through grinding ₂Composite, particle diameter are 0.5 μ m～10 μ m, can directly be used as rubber filler.

Secondly with submicron order C/SiO ₂Composite with 500 ℃～800 ℃ burnings, with the product pickling, makes purity and is higher than 95% in fluidized bed furnace, average grain diameter 30nm～100nm, and specific area is greater than 100m ²The nanometer grade silica of/g.

Prepare the method for active carbon with superhigh specific surface area with rice husk, see patent ZL98114553.1 for details, the processing method of cleaning solution is in the preparation active carbon with superhigh specific surface area process:

(1) processing of cleaning solution when being the feedstock production active carbon with superhigh specific surface area: cleaning solution mesosilicic acid root concentration 0.01～0.1M with potassium hydroxide, treatment temperature is at 0 ℃～90 ℃, feed the carbon dioxide that the rice husk burning produces, control pH value 8～11 forms Ludox, the Ludox Solid-Liquid Separation, the solid phase drying is prepared nanometer grade silica, and granularity 10nm～100nm, liquid phase part are potassium bicarbonate solution.

According to different needs, can adopt two kinds of methods to handle described potassium bicarbonate solution: to make described potassium bicarbonate solution obtain saleratus, be higher than 120 ℃ of heat treatments and obtain potash in the temperature evaporation that is lower than 100 ℃; Perhaps, the aqueous solution that feeds calcium oxide in the solution of described saleratus in a certain way carries out chemical reaction and obtains nanometer grade calcium carbonate or common precipitated calcium carbonate, obtain potassium hydroxide simultaneously, it is recycling that potassium hydroxide can return the activated carbon with high specific surface area operation.

(2) processing of cleaning solution when being the feedstock production active carbon with superhigh specific surface area: cleaning solution mesosilicic acid root concentration 0.01～0.1M with NaOH, treatment temperature is at 0 ℃～90 ℃, feed the carbon dioxide that the rice husk burning produces, control pH value 8～11 forms Ludox, the Ludox Solid-Liquid Separation, the solid phase drying is prepared nanometer grade silica, granularity 10nm～100nm; Liquid phase part is a sodium bicarbonate solution.Sodium bicarbonate solution is carried out chemical reaction with the calcium oxide aqueous solution that feeds in a certain way obtain nanometer grade calcium carbonate or common precipitated calcium carbonate, obtain NaOH simultaneously, it is recycling that NaOH can return the activated carbon with high specific surface area operation.

No matter be to use NaOH or potassium hydroxide, adopt adding calcium oxide method all can make the raw material recycling, use potassium hydroxide also can directly reclaim more economical potash.Add calcium oxide low in price, make the more expensive potassium hydroxide of price (or NaOH) recycling, reduced production cost significantly, high-grade products such as nanometer grade calcium carbonate, nanometer grade silica, nanometer micropore activated carbon with high specific surface area can be competed with common like product on price.

Utilize rice husk to prepare submicron order C/SiO ₂Composite is a kind of new type rubber compound, not only has strengthening action preferably, and has increased substantially the anti-wear performance of rubber.

Because rice husk silicon is evenly distributed in the rice husk, the process conditions of controlling well obtain nanoscale SiO ₂, this and the nanoscale SiO for preparing with chemical reagent ₂Compare, it is simple to have technology, advantages such as low price, and utilized natural resources, and reduced pollution, improved environment, created economic benefit.

Prepare the nanometer micropore activated carbon with high specific surface area from rice husk simultaneously, specific surface surpasses 3500m ²/ g, this is a kind of novel superpower sorbing material, be 3-4 times of common activated carbon adsorptive capacity, and pore size distribution is even, has widened the Application of Brand Active Carbon field greatly.(see patent for details: ZL98114553.1)

In the comprehensive utilization of rice husk, what deserves to be mentioned is the utilization of the rice husk combustion heat, the calorie value of the rice husk combustion heat is 3500-3700 card/Kg, adjust the product mix and technological process just can make to burn by rice husk with heat and plant area, office building, family dependents' dormitory heating etc. in production processes such as charred rice husk, reaction heating, product drying, distilled water preparations and provides, it is all self-supporting with heat to produce like this, live, thereby natural resources have been effectively utilized, saved energy consumption, reduce cost, improved competition capability greatly.

In the research of rice husk comprehensive utilization, another main points are utilizations of combustion tail gas, and this has not only reduced CO ₂Discharge capacity in atmosphere, the residual alkali number in the waste water that neutralized makes waste water reuse, make production line become the cleaning technology production line, make enterprise become pollution-free green environment-friendly type enterprise, and increased new product for enterprise, reduce factory's totle drilling cost, increased economic benefit.

In sum, the method for the invention is fully used this agricultural waste of rice husk, both can prepare nanometer grade silica, nanometer grade calcium carbonate, submicron order C/SiO ₂Composite, can prepare the nanometer micropore activated carbon with high specific surface area again, energy is fully used, eliminate the influence of emission of carbon-dioxide atmospheric ozone layer, make production line become the cleaning technology production line, can make enterprise become pollution-free green environment-friendly type enterprise.

Therefore the method for the invention have technological process simple, easy to make, make rational use of resources, excellent results such as added value of product height, economic benefit and obvious social benefit.

The specific embodiment:

Further set forth the present invention below in conjunction with specific embodiment.

Embodiment 1:

Rice husk 400 ℃ of following charings 1.5 hours, is obtained the charred rice husk thing, grind, obtain average grain diameter and be 2 microns C/SiO through pulverizer ₂Composite; With C/SiO ₂Composite with 600 ℃ of burnings of mean temperature, feeds combustion residue the H of 1M in fluidized bed furnace ₂SO ₄Solution-treated, after the Separation of Solid and Liquid, it is 96% nanometer grade silica that washing and drying can make purity, particle diameter is 60 nanometers.

Embodiment 2:

Condition is with embodiment 1, and going out average grain diameter through FLOTATION SEPARATION is 3 microns C/SiO ₂Composite, burning can obtain the silica of 80 nanometers after the pickling.

Embodiment 3:

Condition replaces the H of 1M with embodiment 1 with the HCl of 1M ₂SO ₄Solution can obtain purity and be 96% silica.

Embodiment 4:

Use patent ZL98114553.1 to prepare process of active carbon, add 4 parts of KOH,, cool off after 1 hour 750 ℃ of activation, it is 3100m that the grinding washing obtains specific area ²The active carbon of/g, obtain to be rich in silicate simultaneously, carbonate, the cleaning solution of potassium ion, adjusting cleaning solution mesosilicic acid root concentration is 0.05M, feeds the carbon dioxide that the rice husk burning produces down at 25 ℃, when the pH value is 10, through separating, wash, drying, obtain the silica that particle diameter is 50 nanometers, purity is more than 99%.

Embodiment 5:

Condition is with embodiment 4, and controlling last pH value is 8, obtains the silica that particle diameter is 100 nanometers.

Embodiment 6:

Condition is with embodiment 4, with after the liquid concentration of separating behind the silicic acid 120 ℃ of following heat treatments, obtain purity and be 98% potash.

Embodiment 7:

Condition, contacts with the aqua calcis fountain the liquid concentration behind the divided silicon colloidal sol with embodiment 4, carries out Separation of Solid and Liquid then, and solid phase obtains precipitated calcium carbonate through washing and drying, and liquid phase obtains potassium hydroxide through concentrating after-baking.

Embodiment 8:

Condition is with embodiment 4, and changing activator into NaOH is 3 parts, and other conditions are with embodiment 5, and embodiment 7, obtain NaOH at last.

Claims

1, a kind of method of comprehensive utilization of rice husk is characterized in that comprising following four steps:

(1) produces submicron order C/SiO ₂Composite: at first the rice husk secluding air is carried out charcoal

Change, carbonization temperature is 300 ℃～500 ℃, and the time is 30～120 minutes, through grinding

Mill is prepared submicron order C/SiO ₂Composite, particle diameter are 0.5 μ m～10 μ m;

(2) produce nanoscale SiO ₂: with submicron order C/SiO ₂Composite is in fluidized bed furnace

With 500 ℃～800 ℃ burnings,, make out purity and be higher than 95%, flat the product pickling

All particle diameter 30nm～100nm, specific area are greater than 100m ²The nanometer grade silica of/g;

(3) processing of cleaning solution in the preparation active carbon with superhigh specific surface area process:

A. when being the feedstock production active carbon with superhigh specific surface area with potassium hydroxide, the processing of cleaning solution

Process is: cleaning solution mesosilicic acid root concentration 0.01～0.1M, treatment temperature 0 ℃～

90 ℃, feed the carbon dioxide that the rice husk burning produces, control pH value 8～11 forms silicon

Colloidal sol, the Ludox Solid-Liquid Separation, solid phase part drying is prepared the nanoscale dioxy

Change silicon, granularity 10nm～100nm; Liquid phase part is a potassium bicarbonate solution, can adopt

Two kinds of methods are handled described potassium bicarbonate solution: described potassium bicarbonate solution is being lower than

The evaporation of 100 ℃ temperature obtains saleratus, obtains carbonic acid being higher than 120 ℃ of heat treatments

Potassium; Perhaps, in described potassium bicarbonate solution, feed the aqueous solutionization of calcium oxide

Learn reaction and obtain nanometer grade calcium carbonate or common precipitated calcium carbonate, obtain hydroxide simultaneously

Potassium;

B. when being the feedstock production active carbon with high specific surface area with NaOH, the processing of cleaning solution

Colloidal sol, the Ludox Solid-Liquid Separation, the solid phase drying is prepared nanometer grade silica, granularity 10nm～100nm; Liquid phase part is a sodium bicarbonate solution, and the aqueous solution that feeds calcium oxide in described sodium bicarbonate solution carries out chemical reaction and obtains nanometer grade calcium carbonate or common precipitated calcium carbonate, obtains NaOH simultaneously; (4) processing of the rice husk combustion heat and tail gas: the production process that the combustion heat can be used for charred rice husk, reaction heating, product drying, distilled water preparation is with heat and plant area, office building, family dependents' dormitory heating; Tail gas carbon dioxide feeds the cleaning solution processing procedure.