CA1088961A - Disposal of fluoride-containing wastes - Google Patents
Disposal of fluoride-containing wastesInfo
- Publication number
- CA1088961A CA1088961A CA301,091A CA301091A CA1088961A CA 1088961 A CA1088961 A CA 1088961A CA 301091 A CA301091 A CA 301091A CA 1088961 A CA1088961 A CA 1088961A
- Authority
- CA
- Canada
- Prior art keywords
- waste
- slurry
- red mud
- acid
- anhydrite
- 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.)
- Expired
Links
Landscapes
- Treatment Of Sludge (AREA)
Abstract
Abstract of the Disclosure A method is disclosed for disposing of acid anhydrite waste which has resulted from the treatment of fluorspar with strong sulphuric acid.
This waste is mixed with red mud solids from the production of alumina from bauxite to form a slurry having 65-80% solids. The waste is comminuted either before or during the mixing with the red mud solids. The proportions of acid anhydrite waste and red mud solids are selected so that, at the end of the mixing procedure, the slurry has a pH value of at least 3. The resultant red mud/acid anhydrite waste slurry is then pumped to a receiving area and allowed to set into a dense, rock-like mass. The invention is particularly useful in the generation of hydrogen fluoride through the reaction of fluorspar with sulphuric acid.
This waste is mixed with red mud solids from the production of alumina from bauxite to form a slurry having 65-80% solids. The waste is comminuted either before or during the mixing with the red mud solids. The proportions of acid anhydrite waste and red mud solids are selected so that, at the end of the mixing procedure, the slurry has a pH value of at least 3. The resultant red mud/acid anhydrite waste slurry is then pumped to a receiving area and allowed to set into a dense, rock-like mass. The invention is particularly useful in the generation of hydrogen fluoride through the reaction of fluorspar with sulphuric acid.
Description
9i~L
The present invention relates to the disposal of fluoride-containin~ wastss and in particular to the waste rssulting from the reaction of fluorspar with strong sulphuric acid to generate hydro~en fluorida. This reaction is carried out on a large scale in connection with the production of aluminium fluoride for use in the electrolyte of electrol~tiG
reduction cells for the production of aluminium.
In the treatment of fluorspar with strong sulphuric acid a substantial exces~ of acid i~ employed. Consequentl~
the solid residue, resulting from the process, is highly acidic. Despite the use of e~cess sulphuric acid, the waste, which is primarily composed of anhydrou~ calcium sulphate, contains substantial quantities of unreacted calcium fluoride and free hydrogen fluoride. ~his waste therefore presents a substantial problem for disposal in an ecologically acceptable manner. In order to satisfy that requirement the pE of the acidic waste should be brought to a value above p~ ~ and more preferably above pH 5, for example pE 6 and the reæidual fluoride should be "locked" in the neutralised waste so that it does not leach out to ~uGh a~ extent as to raise the ~luoride content of neighbouring water courses to an unacceptable level.
We have found that a useful test for audging whether the fluoride is adequately locked into the waste i8 to subaect a batch of neutralised waste material to water leaching for 48 hours. If at the e~d of the third or fourth such leachi~g treatment the extraction of fluoride is found to have reduced to less than 1% of the fluoride content the treatment may be considexed accaptable. However the proce~s of the present in~ention is capable of achieving far superior results to that above indicated.
~ he pre~ent invention ~eeks to lock in the residual fluoride content by neutralisation of the calcium sulphata Y.~-~. . .
: . , , ., . .:
.: . : , . . . .
10~39~L
anhydrite waste to a compaat, rather impervious rock-like state. ~o achieve this result it is necessary to convert the acidic anhydrite waste to gypsum (CaS04.2E20). Conventionally the acid anhydrite waste has been treated with lime or with calcium carbonate, either dry or under aqueous conditions.
Using dry neutralisation it has been necessary to employ a briquetting technique in order to bring the waste into a form in which it could be conveniently transported. ~owever, the ~riquettes are u~stable in the waste disposal area and therefore hazardous from an ecological viewpoint. When using neutrali-sation under aqueous conditions the resultin~ residue has to be stored in unsightly "white mud lake~", leading to pos~ible contamination of water courses not only by dissolved fluoride but al80 by unde~irable finely divided solid particles~
We have now apprecia-ted that the neutrali~ation of the acidic anhydrite waste can be very conveniently effected by the use of a waste material, the so-called "rea mud" re~ulting from -khe Bayer pxocess for the production of alumina from bauxite.
As discharged from a Bayer process plant the red mud is in the form of a slurry containing 20-25% solids a~d 1-2/o soda in solution in the aqueous phase. ~h~ red mud solids co~tain sodalite ~a sodium aluminium silicate complex) which readil~
reacts with mineral a¢ids such as sulphuric acid and hydro-fluoric acid.
~he present in~ention is based on neutralising the free acid content of the acid anhydrite waste by reaction with the sodalite conte~t of the red mud solids. ~he product~ of this reaction have a catalytic effect on the hydration of anhydrite to gyp8um. ~his reaction sequence imparts unique rheological properties to the mix~
According to the present invention, there is provided a method for dispo~ing of acid anhydrite waste, resulting from .
: .
.
the treatment of fluor~par with stro~ sulphuric acid, which co~prises mixing said waste with red mud solid~ from the pro-duction of alumina from bauxite to form a slurry haYi~g 65-8~h ~olids, said waste being comminuted either before or i~ the course of mixi~g with said red mud solid~, the proportions of acid a~hydrite w~ste and red mud ~olid~ bei~g selected 80 that at the end of the mixing procedure the slurry has a pH v~lue of at least 3, the resultant red mud/acid anhydrite waste slurry then being pumped to a receiving area and allowed to ~et into a de~se, rock-like ma~s.
It is a surprisi~g feature of the present inventio~ that the high-solids slurry formed by mixing the red mud ~olids and acidic anhydrits waste ~hould be pumpable.
It is pre~exred that the red mud/acid anhydrite waste slurry should be a~ nearly neutral as possible and for that purpose it is preferred that the relative proportions of the two components should be cho~en to provide a ~lurry which~ after reaction, ha~ a pH in the range of 5-9. ~owever it i~ in no way critical that the pH of the slurry should be withi~ that range.
It is k~own that alumi~ium sulphate and ~odium sulphate act as activator~ for the tran5formatio~ of &nhydrite to gyp~um ~:
and these substance~ are produced in the neutralisation of the exce~s sulphuric acid content of the anhydrite waste~ I~ this trans~ormation a substantial proportion of the water conte~t of the ælurry iæ absorbed as water of crystallisation, so that the slurry on standing at the receivi~g area sets into a rock-like mass which is relati~ely impervious to the passage of waterO
~he imperviousne~s is attributed to the release of silica in the 30 form of an amorphous gel when sodalite is broken down by reac tion with æulphuric acid. On subjecting the æolidified material ~:
to the leaching test sug~ested above, it is found that the rate --3-- :
.
..
. . ., ~ ~. .
9~;1 of extractio~ of both fluoride and sulphate is well within acceptable limits, so that any percolatio~ of the wa5te disposal area by rain or stream water will not lead to unacceptable ¢ontamination of water courses.
While the present procedure for the neutralisation of acidic anhydrite waste may be carried out with a red mud slurry taken directly from the Bayer process plant, it is preferred to filter the red mud slurry, or use other separation methods such as settli~g, to recover part of the soda-containi~g a~u~ous pha3e a~d the~ to re-slurry the moist separated solids i~ a little water, maintaining a high-~olids slurry, before mlxing with the acid anhydrite waste. In this way, the ratio of anhydrite waste to red mud solid~ can be readily adjusted to a desirable level. ~he percentage of solids i~ the final mix can then be controlled by a suitable addition of water. hnother ad~antage of this approach is that more sodalite, and less soda from liquor, is used for the neutralisation and thus more aluminium sulphate and silica are formed. It i8 believed that these two compounds are beneficial in the setting of the mix.
In fact, in test results it has bee~ found that the rate of leaching from the ~eutralisation product, after setti~g, shows some further improveme~t when filtered red mud solids are employed as compared with the use of the raw red mud ~lurry taken direct from the Bayer process plant.
In one series of experiments de~igned to simulate commercial scale eperation acid a~hydrite waste at a tempera-ture in the range of 150-205C ~typical of the discharge temperature from a reactor for generation o~ ~F) was miæed with a red mud slurry withdrawn from a ~ayer process plant at a temperature in the range of 55-70C. ~he resulting slurry had a solids conte~t in the range of 60-75% and after reaction the pH of the slurry ranged from 102 to 8.6. I~ all cases where 896~
the pH value of the slurry was above 3 the mix harde~ed within 5 days. Satisfaotory results were obtained with acid anhydrite wastes having residual free sulphuric acid content~ a~ hîgh as 1~/o and free re idual calcium fluoride contents as high a8 1~/o and as low as 0-5%O In all cases the ~lurries had an ~pparent viscosity ~ufficiently low ~or them to be pumpable7 When a slurry of less than 65% solids conte~t was allowed to set i~
la~ers of a thick~ess of 1-3 inches a thin layer of ~uper~atant water appeared on the top of the set material. It was there-fore concluded that for practical operation it WAS preferableto operate with a slurry having a solids content i~ the region Of 65~ /o.
~ he operation of the process is further described with reference to the accompanying diagrammatic drawing of a plant designed to put the invention into e~fect~
Red mud slurry from a Bayer process plant enters a storage tank 1 via conduit 2. ~imited settlement of the ~lurry may take place in tank 1 and soda-containing liquor ma~ be withdraw~ via overflow pipe 3. Red mud slurry is withdrawn from the bottom Of tank 1 by a slurr~ pump * and forwarded to a paddle mixer 5 at a predetermined rate through a variable opening valve 6 under control of a flow metor 7, excess slurr~
being returned to the tank 1 through the conduit 8~
Acidic anhydrite waste is supplied through conduit 10 and is supplied via a screw conveyor 11 and magnetic hump 12 (a device to trap an~ tramp iron in the anhydrite waste) to paddle mixer 5, in which the two compone~ts are thoroughly mixed for several mi~ute~ to allow i~itial reaction to take place with relea~e of generated C02. ~he slurry is then for-warded to a disintegrator 14 in which the mixi~g is co~tinuedand any remaining coarse lumps of the anhydrite waste or com-pacts ~ormed by red mud/a~hydrite waste reactio~ in mixer 5 are broke~ down to ensure complete conversion of the anhydrite to gypsumO In some instances, particularly where the acid content of the anhydrite waste is 1QW ~and consequentl~ the propor-ti~n of red mud slurry is also low),, the paddle mixer and disintegrator may be replaced by a ball mill. The ælurry from the disintegrator or ball mill is then forwarded by a slurry pump 15 to the disposal area. On reaching the disposal ~ite the slurry is deposited in a thin layer to allow setting to take place quickly, so that it is usually deposited on a mass from earlier operations.
A plant te~t was carried out using the equipment shown in ~igure 1. Several hundred to~s of mix were deposited in a trench-like depression ~nd the physical and economic parametsrs were monitored. ~he mix behaved as predicted in the above small scale tssts with no measurable contamination o~ atmosphere, of sub-surface waters, or of run-offO The compressive strength of mix was over 2~000 pounds per square inch after 20 days of hardening.
' ' ~
The present invention relates to the disposal of fluoride-containin~ wastss and in particular to the waste rssulting from the reaction of fluorspar with strong sulphuric acid to generate hydro~en fluorida. This reaction is carried out on a large scale in connection with the production of aluminium fluoride for use in the electrolyte of electrol~tiG
reduction cells for the production of aluminium.
In the treatment of fluorspar with strong sulphuric acid a substantial exces~ of acid i~ employed. Consequentl~
the solid residue, resulting from the process, is highly acidic. Despite the use of e~cess sulphuric acid, the waste, which is primarily composed of anhydrou~ calcium sulphate, contains substantial quantities of unreacted calcium fluoride and free hydrogen fluoride. ~his waste therefore presents a substantial problem for disposal in an ecologically acceptable manner. In order to satisfy that requirement the pE of the acidic waste should be brought to a value above p~ ~ and more preferably above pH 5, for example pE 6 and the reæidual fluoride should be "locked" in the neutralised waste so that it does not leach out to ~uGh a~ extent as to raise the ~luoride content of neighbouring water courses to an unacceptable level.
We have found that a useful test for audging whether the fluoride is adequately locked into the waste i8 to subaect a batch of neutralised waste material to water leaching for 48 hours. If at the e~d of the third or fourth such leachi~g treatment the extraction of fluoride is found to have reduced to less than 1% of the fluoride content the treatment may be considexed accaptable. However the proce~s of the present in~ention is capable of achieving far superior results to that above indicated.
~ he pre~ent invention ~eeks to lock in the residual fluoride content by neutralisation of the calcium sulphata Y.~-~. . .
: . , , ., . .:
.: . : , . . . .
10~39~L
anhydrite waste to a compaat, rather impervious rock-like state. ~o achieve this result it is necessary to convert the acidic anhydrite waste to gypsum (CaS04.2E20). Conventionally the acid anhydrite waste has been treated with lime or with calcium carbonate, either dry or under aqueous conditions.
Using dry neutralisation it has been necessary to employ a briquetting technique in order to bring the waste into a form in which it could be conveniently transported. ~owever, the ~riquettes are u~stable in the waste disposal area and therefore hazardous from an ecological viewpoint. When using neutrali-sation under aqueous conditions the resultin~ residue has to be stored in unsightly "white mud lake~", leading to pos~ible contamination of water courses not only by dissolved fluoride but al80 by unde~irable finely divided solid particles~
We have now apprecia-ted that the neutrali~ation of the acidic anhydrite waste can be very conveniently effected by the use of a waste material, the so-called "rea mud" re~ulting from -khe Bayer pxocess for the production of alumina from bauxite.
As discharged from a Bayer process plant the red mud is in the form of a slurry containing 20-25% solids a~d 1-2/o soda in solution in the aqueous phase. ~h~ red mud solids co~tain sodalite ~a sodium aluminium silicate complex) which readil~
reacts with mineral a¢ids such as sulphuric acid and hydro-fluoric acid.
~he present in~ention is based on neutralising the free acid content of the acid anhydrite waste by reaction with the sodalite conte~t of the red mud solids. ~he product~ of this reaction have a catalytic effect on the hydration of anhydrite to gyp8um. ~his reaction sequence imparts unique rheological properties to the mix~
According to the present invention, there is provided a method for dispo~ing of acid anhydrite waste, resulting from .
: .
.
the treatment of fluor~par with stro~ sulphuric acid, which co~prises mixing said waste with red mud solid~ from the pro-duction of alumina from bauxite to form a slurry haYi~g 65-8~h ~olids, said waste being comminuted either before or i~ the course of mixi~g with said red mud solid~, the proportions of acid a~hydrite w~ste and red mud ~olid~ bei~g selected 80 that at the end of the mixing procedure the slurry has a pH v~lue of at least 3, the resultant red mud/acid anhydrite waste slurry then being pumped to a receiving area and allowed to ~et into a de~se, rock-like ma~s.
It is a surprisi~g feature of the present inventio~ that the high-solids slurry formed by mixing the red mud ~olids and acidic anhydrits waste ~hould be pumpable.
It is pre~exred that the red mud/acid anhydrite waste slurry should be a~ nearly neutral as possible and for that purpose it is preferred that the relative proportions of the two components should be cho~en to provide a ~lurry which~ after reaction, ha~ a pH in the range of 5-9. ~owever it i~ in no way critical that the pH of the slurry should be withi~ that range.
It is k~own that alumi~ium sulphate and ~odium sulphate act as activator~ for the tran5formatio~ of &nhydrite to gyp~um ~:
and these substance~ are produced in the neutralisation of the exce~s sulphuric acid content of the anhydrite waste~ I~ this trans~ormation a substantial proportion of the water conte~t of the ælurry iæ absorbed as water of crystallisation, so that the slurry on standing at the receivi~g area sets into a rock-like mass which is relati~ely impervious to the passage of waterO
~he imperviousne~s is attributed to the release of silica in the 30 form of an amorphous gel when sodalite is broken down by reac tion with æulphuric acid. On subjecting the æolidified material ~:
to the leaching test sug~ested above, it is found that the rate --3-- :
.
..
. . ., ~ ~. .
9~;1 of extractio~ of both fluoride and sulphate is well within acceptable limits, so that any percolatio~ of the wa5te disposal area by rain or stream water will not lead to unacceptable ¢ontamination of water courses.
While the present procedure for the neutralisation of acidic anhydrite waste may be carried out with a red mud slurry taken directly from the Bayer process plant, it is preferred to filter the red mud slurry, or use other separation methods such as settli~g, to recover part of the soda-containi~g a~u~ous pha3e a~d the~ to re-slurry the moist separated solids i~ a little water, maintaining a high-~olids slurry, before mlxing with the acid anhydrite waste. In this way, the ratio of anhydrite waste to red mud solid~ can be readily adjusted to a desirable level. ~he percentage of solids i~ the final mix can then be controlled by a suitable addition of water. hnother ad~antage of this approach is that more sodalite, and less soda from liquor, is used for the neutralisation and thus more aluminium sulphate and silica are formed. It i8 believed that these two compounds are beneficial in the setting of the mix.
In fact, in test results it has bee~ found that the rate of leaching from the ~eutralisation product, after setti~g, shows some further improveme~t when filtered red mud solids are employed as compared with the use of the raw red mud ~lurry taken direct from the Bayer process plant.
In one series of experiments de~igned to simulate commercial scale eperation acid a~hydrite waste at a tempera-ture in the range of 150-205C ~typical of the discharge temperature from a reactor for generation o~ ~F) was miæed with a red mud slurry withdrawn from a ~ayer process plant at a temperature in the range of 55-70C. ~he resulting slurry had a solids conte~t in the range of 60-75% and after reaction the pH of the slurry ranged from 102 to 8.6. I~ all cases where 896~
the pH value of the slurry was above 3 the mix harde~ed within 5 days. Satisfaotory results were obtained with acid anhydrite wastes having residual free sulphuric acid content~ a~ hîgh as 1~/o and free re idual calcium fluoride contents as high a8 1~/o and as low as 0-5%O In all cases the ~lurries had an ~pparent viscosity ~ufficiently low ~or them to be pumpable7 When a slurry of less than 65% solids conte~t was allowed to set i~
la~ers of a thick~ess of 1-3 inches a thin layer of ~uper~atant water appeared on the top of the set material. It was there-fore concluded that for practical operation it WAS preferableto operate with a slurry having a solids content i~ the region Of 65~ /o.
~ he operation of the process is further described with reference to the accompanying diagrammatic drawing of a plant designed to put the invention into e~fect~
Red mud slurry from a Bayer process plant enters a storage tank 1 via conduit 2. ~imited settlement of the ~lurry may take place in tank 1 and soda-containing liquor ma~ be withdraw~ via overflow pipe 3. Red mud slurry is withdrawn from the bottom Of tank 1 by a slurr~ pump * and forwarded to a paddle mixer 5 at a predetermined rate through a variable opening valve 6 under control of a flow metor 7, excess slurr~
being returned to the tank 1 through the conduit 8~
Acidic anhydrite waste is supplied through conduit 10 and is supplied via a screw conveyor 11 and magnetic hump 12 (a device to trap an~ tramp iron in the anhydrite waste) to paddle mixer 5, in which the two compone~ts are thoroughly mixed for several mi~ute~ to allow i~itial reaction to take place with relea~e of generated C02. ~he slurry is then for-warded to a disintegrator 14 in which the mixi~g is co~tinuedand any remaining coarse lumps of the anhydrite waste or com-pacts ~ormed by red mud/a~hydrite waste reactio~ in mixer 5 are broke~ down to ensure complete conversion of the anhydrite to gypsumO In some instances, particularly where the acid content of the anhydrite waste is 1QW ~and consequentl~ the propor-ti~n of red mud slurry is also low),, the paddle mixer and disintegrator may be replaced by a ball mill. The ælurry from the disintegrator or ball mill is then forwarded by a slurry pump 15 to the disposal area. On reaching the disposal ~ite the slurry is deposited in a thin layer to allow setting to take place quickly, so that it is usually deposited on a mass from earlier operations.
A plant te~t was carried out using the equipment shown in ~igure 1. Several hundred to~s of mix were deposited in a trench-like depression ~nd the physical and economic parametsrs were monitored. ~he mix behaved as predicted in the above small scale tssts with no measurable contamination o~ atmosphere, of sub-surface waters, or of run-offO The compressive strength of mix was over 2~000 pounds per square inch after 20 days of hardening.
' ' ~
Claims (2)
1. A method for disposing of acid anhydrite waste, resulting from the treatment of fluorspar with strong sulphuric acid, which comprises mixing said waste with red mud solids from the production of alumina from bauxite to form a slurry having 65-85% solids, said waste being comminuted either before or in the course of mixing with said red mud solids, the proportions of acid anhydrite waste and red mud solids being selected so that at the end of the mixing procedure the slurry has a pH value of at least 3, the resultant red mud/acid anhydrite waste slurry then being pumped to a receiving area and allowed to set into a dense, rock-like mass.
2. A method according to claim 1 in which the propor-tions of red mud solids and acid anhydrite waste are chosen to raise the pH of the slurry to a value in the range of 5-9.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1561377 | 1977-04-14 | ||
| GB15613/77 | 1977-04-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1088961A true CA1088961A (en) | 1980-11-04 |
Family
ID=10062293
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA301,091A Expired CA1088961A (en) | 1977-04-14 | 1978-04-13 | Disposal of fluoride-containing wastes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1088961A (en) |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7077963B2 (en) | 2000-10-27 | 2006-07-18 | Nauveau Technology Investments | Processes for water treatment |
| US9023301B2 (en) | 2012-01-10 | 2015-05-05 | Orbite Aluminae Inc. | Processes for treating red mud |
| US9150428B2 (en) | 2011-06-03 | 2015-10-06 | Orbite Aluminae Inc. | Methods for separating iron ions from aluminum ions |
| US9181603B2 (en) | 2012-03-29 | 2015-11-10 | Orbite Technologies Inc. | Processes for treating fly ashes |
| US9290828B2 (en) | 2012-07-12 | 2016-03-22 | Orbite Technologies Inc. | Processes for preparing titanium oxide and various other products |
| US9353425B2 (en) | 2012-09-26 | 2016-05-31 | Orbite Technologies Inc. | Processes for preparing alumina and magnesium chloride by HCl leaching of various materials |
| US9410227B2 (en) | 2011-05-04 | 2016-08-09 | Orbite Technologies Inc. | Processes for recovering rare earth elements from various ores |
| US9534274B2 (en) | 2012-11-14 | 2017-01-03 | Orbite Technologies Inc. | Methods for purifying aluminium ions |
| US9945009B2 (en) | 2011-03-18 | 2018-04-17 | Orbite Technologies Inc. | Processes for recovering rare earth elements from aluminum-bearing materials |
| US10174402B2 (en) | 2011-09-16 | 2019-01-08 | Orbite Technologies Inc. | Processes for preparing alumina and various other products |
| CN110283652A (en) * | 2019-05-08 | 2019-09-27 | 北京城建九混凝土有限公司 | A kind of pumping aid agent and its application prepared using concrete waste grout |
-
1978
- 1978-04-13 CA CA301,091A patent/CA1088961A/en not_active Expired
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7077963B2 (en) | 2000-10-27 | 2006-07-18 | Nauveau Technology Investments | Processes for water treatment |
| US9945009B2 (en) | 2011-03-18 | 2018-04-17 | Orbite Technologies Inc. | Processes for recovering rare earth elements from aluminum-bearing materials |
| US9410227B2 (en) | 2011-05-04 | 2016-08-09 | Orbite Technologies Inc. | Processes for recovering rare earth elements from various ores |
| US9150428B2 (en) | 2011-06-03 | 2015-10-06 | Orbite Aluminae Inc. | Methods for separating iron ions from aluminum ions |
| US10174402B2 (en) | 2011-09-16 | 2019-01-08 | Orbite Technologies Inc. | Processes for preparing alumina and various other products |
| US9023301B2 (en) | 2012-01-10 | 2015-05-05 | Orbite Aluminae Inc. | Processes for treating red mud |
| US9556500B2 (en) | 2012-01-10 | 2017-01-31 | Orbite Technologies Inc. | Processes for treating red mud |
| US9181603B2 (en) | 2012-03-29 | 2015-11-10 | Orbite Technologies Inc. | Processes for treating fly ashes |
| US9290828B2 (en) | 2012-07-12 | 2016-03-22 | Orbite Technologies Inc. | Processes for preparing titanium oxide and various other products |
| US9353425B2 (en) | 2012-09-26 | 2016-05-31 | Orbite Technologies Inc. | Processes for preparing alumina and magnesium chloride by HCl leaching of various materials |
| US9534274B2 (en) | 2012-11-14 | 2017-01-03 | Orbite Technologies Inc. | Methods for purifying aluminium ions |
| CN110283652A (en) * | 2019-05-08 | 2019-09-27 | 北京城建九混凝土有限公司 | A kind of pumping aid agent and its application prepared using concrete waste grout |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1088961A (en) | Disposal of fluoride-containing wastes | |
| US5078795A (en) | In-situ formation of soluble silicates from biogenetic silica in chemical fixation/solidification treatment of wastes | |
| CN106882932B (en) | A kind of method of comprehensive utilization of red mud | |
| EP0252099A1 (en) | Magnesium cement | |
| CN106904807A (en) | A kind of method that phosphorus is reclaimed from dewatered sludge | |
| CA1216008A (en) | Treatment of scrap lining material from aluminium reduction cells | |
| CN105905933A (en) | Process for preparing high-purity artificial fluorite by recovering fluoride-containing wastewater | |
| CA1230350A (en) | Process for manufacturing hydraulic binders | |
| CN110204237A (en) | The production method of cement retarder | |
| CN109179476B (en) | Method for controlling water content of titanium gypsum | |
| KR0175069B1 (en) | Work-up of waste materials from barium or strontium sulfide leaching | |
| CN104843750B (en) | A kind of method that aluminum in Bayer process red mud is become aluminium oxide thing phase from calcium aluminosilicate hydrate thing inversion of phases | |
| CN109502655A (en) | A kind of production technology of bodied ferric sulfate | |
| CN106145164A (en) | The method preparing lithium carbonate from lepidolite | |
| CN101830613B (en) | Method for manufacturing autoclaved sand-lime brick or flyash brick as well as fertilizer and grease by sludge | |
| US5071632A (en) | Process for preparing crystals of anhydrous sodium sulfide | |
| CN105883884A (en) | Method for preparing industrial calcium chloride from thiourea waste residues | |
| CN107683262A (en) | Recovery method, fertilizer and the fertilizer material and yellow phosphorus raw material of the recovery system of phosphorus in processed water, the phosphorus in processed water | |
| WO2024051103A1 (en) | Phosphogypsum recovery method | |
| CN109970383B (en) | Production process for manufacturing accelerating agent by using water purifying agent waste residues | |
| CN110304850A (en) | A method of alpha semi-hydrated gypsum is produced based on titanium gypsum | |
| CN113105202B (en) | Full-solid waste material and preparation method and application thereof | |
| JPH0759171B2 (en) | Manufacture method of artificial fishing reef | |
| CN106007797B (en) | Cement-based penetrant curing agent | |
| CN104944736A (en) | Integral treatment method of dehydration and solidification of sludge |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |