CN103771430B - Method for preparing sodium metasilicate and light calcium carbonate with green liquid generated in alkali recovery in papermaking by straw pulp - Google Patents
Method for preparing sodium metasilicate and light calcium carbonate with green liquid generated in alkali recovery in papermaking by straw pulp Download PDFInfo
- Publication number
- CN103771430B CN103771430B CN201410048704.6A CN201410048704A CN103771430B CN 103771430 B CN103771430 B CN 103771430B CN 201410048704 A CN201410048704 A CN 201410048704A CN 103771430 B CN103771430 B CN 103771430B
- Authority
- CN
- China
- Prior art keywords
- calcium carbonate
- silicic acid
- green liquor
- papermaking
- straw pulp
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Paper (AREA)
Abstract
The invention provides a method for preparing sodium metasilicate and light calcium carbonate with a green liquid generated in alkali recovery in papermaking by straw pulp. The method comprises steps of purifying a green liquid generated in a conventional alkali recovery technology in papermaking by straw pulp, introducing carbon dioxide gas into the purified green liquid so as to form a silicic acid suspension liquid, carrying out solid-liquid separation on the silicic acid suspension liquid so as to prepare silicic acid; heating up and reacting the silicic acid and caustic soda so as to obtain liquid sodium metasilicate; causticizing the mother liquid with silicic acid filtered and calcium hydroxide so as to obtain liquid sodium hydroxide and crude silicone-free calcium carbonate, then refining the crude calcium carbonate so as to obtain light calcium carbonate slurry for papermaking. The method overcomes the technical obstacle that silicon resource in the green liquid generated in alkali recovery in papermaking by straw pulp cannot be recycled, thoroughly solves the problem of environment pollution caused by alkali recovery in papermaking by straw pulp, and thoroughly recycles available resource in alkali recover in papermaking by straw pulp and realizes cyclic utilization. The technological process is simple and clean, does not discharge pollutants, is easy to implement, and has remarkable social environment benefits and obvious economic benefits.
Description
Technical field
The present invention relates to the alkali recovery technology of papermaking straw pulp, particularly utilize papermaking straw pulp alkali collection green liquor to produce the method for Starso, light calcium carbonate.
Background technology
Paper industry for raw material, adopts the paper pulp of the chemical process such as soda processes, sulphate process manufacture to be called straw pulp with herbaceous plant such as bamboo, reed, bagasse, wheat straws.The brown-black liquid produced in pulping process is referred to as black liquor, and black liquor is the main severe contamination source of paper industry.Although the alkali recovery technology equipment of advanced practicality of having gone into operation is installed by domestic paper-making pulping enterprise, certain effect is served to energy-saving and emission-reduction, but because herbaceous plant is different from xylophyta, there is the characteristic that dioxide-containing silica is higher, so in alkali recovery process, the comprehensive utilization ratio of straw pulp black liquor is still on the low side, even there is the problem of secondary pollution.Silicon-dioxide contained by herbaceous plant mainly concentrates on the positions such as the blade of plant and sheath joint, and in pulping process, the sodium oxide of the silicon-dioxide in herbaceous plant in cooking liquor is combined and forms water glass and be dissolved in black liquor; Black liquor, after inspissation, in the melts that alkali recovery furnace combustion is formed, can contain the soluble glass of more than 10%.Described melts, with after water dissolution, because containing a small amount of ironic hydroxide in its composition in green, therefore is called green liquor.The main component of this green liquor is sodium carbonate, water glass and sodium sulphite, also containing a small amount of sodium hydroxide and sodium sulfate etc.The causticization process of existing papermaking straw pulp alkali collection is directly joined in green liquor by unslaked lime, and unslaked lime and water are reacted and generates calcium hydroxide, calcium hydroxide carries out causticizing reaction with the sodium carbonate in green liquor again, obtains sodium hydroxide and calcium carbonate; Water glass simultaneously in green liquor can react with calcium hydroxide, and generate sodium hydroxide and Calucium Silicate powder, Calucium Silicate powder is present in calcium carbonate jointly with impurity such as the carbon granule in green liquor, residual alkali, dust, defines siliceous crude product calcium carbonate.Up to the present, for siliceous crude product calcium carbonate, the recycling of resource utilization cannot also be obtained.Thus accumulation the simple landfill of siliceous crude product calcium carbonate or directly can only be dumped by most papermaking straw pulp enterprise, and such processing mode, not only occupies cultivated land, destroyed land resource, also can contaminated land and underground water, even can bring serious destruction to ecotope.
Apply the recycling which kind of technique means realizes the resource utilization of described siliceous crude product calcium carbonate, and thoroughly solve the pollution problem that straw pulp alkali collection brings to environment, be the research topic paid close attention to of scientific and technical personnel in the industry always.
Summary of the invention
The present invention proposes the method utilizing papermaking straw pulp alkali collection green liquor to produce Starso, light calcium carbonate, its object is to, by dissecting the technology drawback existed in existing papermaking straw pulp alkali recovery process process, and for the technology barrier that this technology drawback occurs, eliminate from root the pollution that straw pulp alkali collection brings to environment, and realize cleaning from straw pulp alkali collection green liquor, obtaining to resource utilization Starso and paper grade (stock) light calcium carbonate product.
Technical solution of the present invention:
First, purifying treatment is carried out to the green liquor that papermaking straw pulp alkali collection common process produces: the impurity such as the carbon granule in filtering green liquor, dust; Then pass into carbon dioxide in green liquor after cleaning, form silicic acid suspensions; Silicic acid suspensions is carried out solid-liquid separation, obtains silicic acid filter cake, silicic acid filter cake and caustic soda carry out reacting by heating, obtain liquid Starso; And be separated after mother liquor and calcium hydroxide carry out causticizing reaction, obtain without silicon crude product calcium carbonate; Re-refine without silicon crude product calcium carbonate, obtain paper grade (stock) light calcium carbonate slip, realize resource utilization recycling.
The concrete technology step of the inventive method is:
One, green liquor is filtered.With the impurity such as carbon granule, dust in accurate filter filtering green liquor, until the clear appearance of green liquor is transparent.
Two, silicic acid is prepared.Pass into carbon dioxide in green liquor after cleaning, the water glass in carbonic acid gas and green liquor is reacted, along with the carrying out of reaction, green liquor starts to become muddy, until have a large amount of White Flocculus to occur in green liquor, as the pH=9 of green liquor, stopped reaction, obtains silicic acid suspensions; Silicic acid suspensions is carried out solid-liquid separation, obtains silicic acid filter cake; The mother liquor of filtering silicic acid gives over to for subsequent use.The chemical equation of this step is:
Na
2SiO
3+CO
2+H
2O ==H
2SiO
3↓+Na
2CO
3
Three, Starso is produced.Silicic acid filter cake step 2 obtained and caustic soda react in a heated condition, obtain liquid Starso.Its chemical equation is:
H
2SiO
3+2NaOH== Na
2SiO
3+2H
2O
Four, preparation is without silicon crude product calcium carbonate.After the mother liquor of filtering silicic acid step 2 obtained and calcium hydroxide carry out causticizing reaction, material is done solid-liquid separation, the liquid phase thing obtained is liquid sodium hydroxide, is back to slurrying workshop section; The filter cake obtained is without silicon crude product calcium carbonate.Its chemical equation is:
Na
2CO
3+Ca(OH)
2==2NaOH+CaCO
3
Five, light calcium carbonate slip is produced.What step 4 obtained refines without silicon crude product calcium carbonate filter cake, comprises the treatment process of slurrying, screening removal of impurities, decolouring bleaching, carbonation reaction, obtains paper grade (stock) light calcium carbonate slip.
The concrete technology of further technical solution of the present invention is:
Described produces Starso, is according to step 3, by silicic acid (by SiO
2meter) with caustic soda (by Na
2o counts) weigh with the ratio of 1:1.03 mass parts, and after Homogeneous phase mixing, be placed in heating container and heat, when the temperature of reaction mass reaches 90-100 DEG C, when silicic acid all dissolves, stopped reaction, treat that material is cooled to 40-50 DEG C, namely obtain the liquid Starso product that modulus is 0.97.
Described produces light calcium carbonate slip, is that add process water, be modulated into without silicon crude product calcium carbonate slip, the solid content controlled without silicon crude product calcium carbonate in slip is 15-20% described without in silicon crude product calcium carbonate filter cake; Then by sieving without silicon crude product calcium carbonate slip 325 object mesh screens of modulating, the slip under collection screen after removal of impurities, then carry out decolouring bleaching by the industrial grade hydrogen peroxide accounting for slurry body accumulated amount 0.1-0.5%, both react 30-40 minute; Finally be placed in container by the slip after bleaching, pass into carbon dioxide, carry out carbonation reaction, as the pH=7 of slip, stopped reaction, namely obtains the light calcium carbonate slip conformed to quality requirements for papermaking filler.
Beneficial effect of the present invention:
(1) the present invention utilizes general chemistry principle, and eliminating silicon resource in papermaking straw pulp alkali collection green liquor can not the technology barrier of reuse, produces Starso with silicic acid; The mother liquor of filtering silicic acid and calcium hydroxide are carried out causticizing reaction, obtains liquid sodium hydroxide and without silicon crude product calcium carbonate, liquid sodium hydroxide is cycled to used in paper-making pulping; Without silicon crude product calcium carbonate by refining, obtain light calcium carbonate slip, for papermaking filler.The present invention, while having eradicated papermaking straw pulp alkali collection environmental pollution, solves again the technical barrier that numerous papermaking enterprise is in the urgent need to address, makes by product in straw pulp alkali collection green liquor obtain recycle.
(2) the present invention develops waste resource, has thoroughly reclaimed the available stock in papermaking straw pulp alkali recovery process with simple technical process, obtains Starso, paper grade (stock) light calcium carbonate product.Wherein, Starso is classified as " fine chemicals that China first develops " and " China's inorganic chemical product development priority " by country.The preparation of usual Starso is by quartz and soda ash, and under the high temperature of 1000-1300 DEG C, congruent melting generates, or after react by thick water solution (water glass or sodium silicate) and the soda lye of Starso, through concentrated, crystallization, is separated, dry preparation and obtaining.Starso all has application at multiple industrial circle, and demand is quite large; Light calcium carbonate is one of mineral filler that purposes is the widest, and especially in paper industry, be weighting agent with calcium carbonate, loading level reaches 5-20%, not only reduces cost, also improves intensity and the whiteness of paper simultaneously, has significant economic benefit.
(3) present invention process process cleans, non-pollutant discharge, easy to implement, there is significant social benefit and environmental benefit.
Accompanying drawing explanation
Accompanying drawing is technical process block diagram of the present invention.
Embodiment
Following illustrative example, is described further technical solution of the present invention:
Embodiment one:
(1) Starso is produced: get the green liquor 1L that papermaking straw pulp alkali collection common process produces, carry out vacuum filtration with 4G sand core funnel under normal temperature, obtain as clear as crystal green liquor; Pass into carbon dioxide in green liquor after this purification, after reaction certain hour, green liquor starts muddiness, and along with the carrying out of reaction, have a large amount of White Flocculus to occur in green liquor, when recording the pH=9 of liquid, stopped reaction, obtains silicic acid suspensions; Silicic acid suspensions is carried out vacuum filtration, obtains silicic acid filter cake, claim the quality of silicic acid filter cake is 114.5g; The volume of mother liquor (green liquor of filtering silicic acid) is 0.85L; Record in 114.5g silicic acid filter cake, the quality of silicon-dioxide is 6.396g, and 114.5g silicic acid filter cake is inserted in 250mL beaker, add the caustic soda 8.67g that sodium hydrate content is 98% again, carry out reacting by heating, when temperature of reaction reaches 95 DEG C, silicic acid all dissolves, and stops heating; When temperature of charge is down to 45 DEG C, obtain the liquid Starso that modulus is 0.97, its quality is 123g.
(2) light calcium carbonate slip is produced.In the 0.85L mother liquor (quality recording wherein sodium carbonate is 127.5g) above-mentioned steps obtained, add calcium hydroxide 100g, react 1 hour at temperature 90-95 DEG C, then do solid-liquid separation, the liquid phase thing obtained is liquid sodium hydroxide, and concentration is 107g/L; The solid formation obtained is without silicon crude product calcium carbonate filter cake, and quality is 152g; Again this is inserted in container without silicon crude product calcium carbonate filter cake, add 700mL process water, carry out stirring and size mixing, after being uniformly dispersed, carry out screening removal of impurities by 325 order circular sieve, collection screen excess; In screenings, add 2mL industrial grade hydrogen peroxide carry out decolouring bleaching, the reaction times is 30 minutes; After reaction terminates, by this slip and carbon dioxide gas precursor reactant, as the pH=7 of slip, stopped reaction, obtains light calcium carbonate slip.
Embodiment two:
(1) Starso is produced: get the green liquor 10L that papermaking straw pulp alkali collection common process produces, carry out vacuum filtration with 4G sand core funnel under normal temperature, obtain as clear as crystal green liquor; Pass into carbon dioxide in green liquor after this purification, after reaction certain hour, green liquor starts muddiness, and along with the carrying out of reaction, have a large amount of White Flocculus to occur in green liquor, when recording the pH=9 of liquid, stopped reaction, obtains silicic acid suspensions; Silicic acid suspensions is carried out vacuum filtration, obtains silicic acid filter cake, claim the quality of silicic acid filter cake is 980g; The volume of mother liquor (green liquor after filtering silicic acid) is 9L; Record in 980g silicic acid filter cake, the quality of silicon-dioxide is 60g, and 980g silicic acid filter cake is inserted in 3000mL beaker, add the caustic soda 81g that sodium hydrate content is 98% again, carry out reacting by heating, when temperature of reaction reaches 95 DEG C, silicic acid all dissolves, and stops heating; When temperature of charge is down to 45 DEG C, obtain the liquid Starso that modulus is 0.97, its quality is 1060g.
(2) light calcium carbonate slip is produced.In the 9L mother liquor (quality recording wherein sodium carbonate is 1260g) (one) step obtained, add calcium hydroxide 1000g, react 1 hour at temperature 90-95 DEG C, then do solid-liquid separation, the liquid phase thing obtained is liquid sodium hydroxide, and concentration is 95g/L; The solid formation obtained is without silicon crude product calcium carbonate filter cake, and quality is 1352g; Again this is inserted in container without silicon crude product calcium carbonate filter cake, add 7000mL process water, carry out stirring and size mixing, after being uniformly dispersed, carry out screening removal of impurities by 325 order circular sieve, collection screen excess; In screenings, add 30mL industrial grade hydrogen peroxide carry out decolouring bleaching, the reaction times is 30 minutes; After reaction terminates, by this slip and carbon dioxide gas precursor reactant, as the pH=7 of slip, stopped reaction, obtains light calcium carbonate slip.
To sum up, invention achieves the goal of the invention of expection.
Claims (4)
1. utilize papermaking straw pulp alkali collection green liquor to produce the method for Starso, light calcium carbonate, it is characterized in that: the method carries out purifying treatment to the green liquor that papermaking straw pulp alkali collection common process produces: the carbon granule in filtering green liquor, dust impurity; Pass into carbon dioxide in green liquor after cleaning, form silicic acid suspensions; Silicic acid suspensions is carried out solid-liquid separation, obtains silicic acid filter cake, silicic acid filter cake and caustic soda carry out reacting by heating, obtain liquid Starso; And be separated after mother liquor and calcium hydroxide carry out causticizing reaction, obtain without silicon crude product calcium carbonate; Re-refine without silicon crude product calcium carbonate, obtain paper grade (stock) light calcium carbonate slip, realize resource utilization recycling.
2. the method utilizing papermaking straw pulp alkali collection green liquor to produce Starso, light calcium carbonate according to claim 1, is characterized in that: the concrete technology step of the method is:
Step one, filtration green liquor, with the carbon granule in accurate filter filtering green liquor, dust impurity, until the clear appearance of green liquor is transparent;
Step 2, prepare silicic acid, carbon dioxide is passed in green liquor after cleaning, water glass in carbonic acid gas and green liquor is reacted, along with the carrying out of reaction, green liquor starts to become muddy, until have a large amount of White Flocculus to occur in green liquor, as the pH=9 of green liquor, stopped reaction, obtains silicic acid suspensions; Silicic acid suspensions is carried out solid-liquid separation, obtains silicic acid filter cake; The mother liquor of filtering silicic acid gives over to for subsequent use;
Step 3, produce Starso, silicic acid filter cake step 2 obtained and caustic soda react in a heated condition, obtain liquid Starso;
Step 4, prepare crude product calcium carbonate, after the mother liquor of filtering silicic acid step 2 obtained and calcium hydroxide carry out causticizing reaction, material is done solid-liquid separation, the liquid phase thing obtained is liquid sodium hydroxide, is back to slurrying workshop section; The filter cake obtained is without silicon crude product calcium carbonate;
Step 5, produce light calcium carbonate slip, what step 4 obtained refines without silicon crude product calcium carbonate filter cake, comprises the treatment process of slurrying, screening removal of impurities, decolouring bleaching, carbonation reaction, obtains paper grade (stock) light calcium carbonate slip.
3. the method utilizing papermaking straw pulp alkali collection green liquor to produce Starso, light calcium carbonate according to claim 2, is characterized in that:
Described produces Starso, is according to step 3, silicic acid is pressed SiO
2meter and caustic soda press Na
2o counts, and weighs with the ratio of 1:1.03 mass parts, and after Homogeneous phase mixing, be placed in heating container to heat, when the temperature of reaction mass reaches 90-100 DEG C, when silicic acid all dissolves, stopped reaction, treats that material is cooled to 40-50 DEG C, namely obtains the liquid Starso product that modulus is 0.97.
4. the method utilizing papermaking straw pulp alkali collection green liquor to produce Starso, light calcium carbonate according to claim 2, it is characterized in that: described produces light calcium carbonate slip, without in silicon crude product calcium carbonate filter cake described, add process water, be modulated into without silicon crude product calcium carbonate slip, the solid content controlled without silicon crude product calcium carbonate in slip is 15-20%; Then sieved by the slip modulated 325 object mesh screens, the slip under collection screen after removal of impurities, then carry out decolouring bleaching by the industrial grade hydrogen peroxide accounting for slurry body accumulated amount 0.1-0.5%, both react 30-40 minute; Finally be placed in container by the slip after bleaching, pass into carbon dioxide, carry out carbonation reaction, as the pH=7 of slip, stopped reaction, namely obtains the light calcium carbonate slip conformed to quality requirements for papermaking filler.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410048704.6A CN103771430B (en) | 2014-02-12 | 2014-02-12 | Method for preparing sodium metasilicate and light calcium carbonate with green liquid generated in alkali recovery in papermaking by straw pulp |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410048704.6A CN103771430B (en) | 2014-02-12 | 2014-02-12 | Method for preparing sodium metasilicate and light calcium carbonate with green liquid generated in alkali recovery in papermaking by straw pulp |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103771430A CN103771430A (en) | 2014-05-07 |
| CN103771430B true CN103771430B (en) | 2015-06-17 |
Family
ID=50564269
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410048704.6A Active CN103771430B (en) | 2014-02-12 | 2014-02-12 | Method for preparing sodium metasilicate and light calcium carbonate with green liquid generated in alkali recovery in papermaking by straw pulp |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103771430B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104310451A (en) * | 2014-09-28 | 2015-01-28 | 中国制浆造纸研究院 | Preparation method of aragonite type white mud calcium carbonate |
| CN106395878A (en) * | 2015-08-03 | 2017-02-15 | 海南金海浆纸业有限公司 | Method for preparing calcium carbonate filler for papermaking from wood pulp white mud and calcium carbonate filler |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101391794A (en) * | 2008-10-24 | 2009-03-25 | 魏湘 | Novel method for preparing light calcium carbonate by recovering solid white slime through alkaline pulping |
| CN101700901A (en) * | 2009-11-25 | 2010-05-05 | 王冬生 | Novel method for producing light calcium carbonate (CaCO3) from white clay generated from alkali recovering in paper-making industry |
| CN102619123A (en) * | 2012-03-16 | 2012-08-01 | 陕西科技大学 | Method for removing silicon from green liquor through synergism of calcium oxide, carbon dioxide and aluminum-containing compound |
| CN102653411A (en) * | 2012-05-16 | 2012-09-05 | 山东山大华特科技股份有限公司 | Process for preparing light-weight calcium carbonate by recycling white mud by alkali |
-
2014
- 2014-02-12 CN CN201410048704.6A patent/CN103771430B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101391794A (en) * | 2008-10-24 | 2009-03-25 | 魏湘 | Novel method for preparing light calcium carbonate by recovering solid white slime through alkaline pulping |
| CN101700901A (en) * | 2009-11-25 | 2010-05-05 | 王冬生 | Novel method for producing light calcium carbonate (CaCO3) from white clay generated from alkali recovering in paper-making industry |
| CN102619123A (en) * | 2012-03-16 | 2012-08-01 | 陕西科技大学 | Method for removing silicon from green liquor through synergism of calcium oxide, carbon dioxide and aluminum-containing compound |
| CN102653411A (en) * | 2012-05-16 | 2012-09-05 | 山东山大华特科技股份有限公司 | Process for preparing light-weight calcium carbonate by recycling white mud by alkali |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103771430A (en) | 2014-05-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102976387B (en) | Improved preparation technology of white mud calcium carbonate for papermaking filler | |
| CN101391794B (en) | Novel method for preparing light calcium carbonate by recovering solid white slime through alkaline pulping | |
| CN101020182B (en) | Process of comprehensively utilizing caustic sludge from papermaking industry | |
| WO2003066961A1 (en) | A process of recovering alkali from black liquor of papermaking | |
| CN108840361B (en) | A method of high-purity calcium carbonate is refined using green liquor causticizing | |
| CN101700901A (en) | Novel method for producing light calcium carbonate (CaCO3) from white clay generated from alkali recovering in paper-making industry | |
| CN107416877A (en) | The technique of organic matter, iron and silica in a kind of removing sodium aluminate solution | |
| CN1641100A (en) | Method for recovering superfine calcium carbonate by clean causticization of green liquor | |
| CN103771430B (en) | Method for preparing sodium metasilicate and light calcium carbonate with green liquid generated in alkali recovery in papermaking by straw pulp | |
| CN106395878A (en) | Method for preparing calcium carbonate filler for papermaking from wood pulp white mud and calcium carbonate filler | |
| CN109052447A (en) | Pass through the brightness improvement of the lime causticization product of predigestion | |
| EP0549323B1 (en) | Process for the preparation of amorphous silica | |
| US5705031A (en) | Process for removing and washing dregs from green liquor in a kraft pulp mill | |
| CN1047573C (en) | Telchnological process of sodium method producing bleaching powder extract | |
| CN103215849A (en) | Method for recycling white-clay refined paper calcium carbonate filler by improved soda-process pulping alkali | |
| CN103319098B (en) | A kind of method utilizing pulping and paper-making white clay to produce glass fibre | |
| FI98225C (en) | Procedure for Removing Harmful Impurities in Alkaline Delignification of Cellulosic Material | |
| CN101805004A (en) | Method for producing calcium hydroxide and co-producing industrial salt and carbon powder by using carbide slag | |
| CN101823737B (en) | Method for co-production of ultra-fine calcium carbonate and sodium silicate in preparation of light magnesium carbonate by chlor-alkali brine sludge | |
| CN103180506A (en) | Method for comprehensively utilizing solid waste during soda recovery in papermaking industry | |
| CN103754918A (en) | Method for preparing alkali-recovery lime mud free of components with fine particle sizes | |
| CN109279637B (en) | Method for refining filler calcium carbonate by recovering white mud from chemical sulfate wood pulp alkali | |
| CN113443737B (en) | Process for preparing modified straw pulp papermaking white mud and process for producing gypsum through desulfurization | |
| CN101792166A (en) | Method for producing blocky sodium hydroxide and calcium carbonate by using carbide slag | |
| CN211419588U (en) | Waste recycling system in caustic soda production process |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |