CA1168204A - Grinding of titaniferous ores to enhance recovery of titanium dioxide - Google Patents
Grinding of titaniferous ores to enhance recovery of titanium dioxideInfo
- Publication number
- CA1168204A CA1168204A CA000396079A CA396079A CA1168204A CA 1168204 A CA1168204 A CA 1168204A CA 000396079 A CA000396079 A CA 000396079A CA 396079 A CA396079 A CA 396079A CA 1168204 A CA1168204 A CA 1168204A
- Authority
- CA
- Canada
- Prior art keywords
- ore
- titanium dioxide
- polyol
- titaniferous
- comminution
- 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
- Manufacture And Refinement Of Metals (AREA)
Abstract
25,584 Title: IMPROVED GRINDING OF TITANIFEROUS ORES TO
ENHANCE RECOVERY OF TITANIUM DIOXIDE
ABSTRACT OF THE DISCLOSURE
Significant enhancement of titanium dioxide re-covery from a titaniferous ore is achieved by improving the efficiency of the comminution of the ore with the use of polyols of the formula:
R - C -(- R'OH)3 wherein R is alkyl (C1-C4), or hydroxyalkyl (C1-C4) contain-ing up to 3 hydroxy groups, and wherein R' is alkylene (C1-C3).
ENHANCE RECOVERY OF TITANIUM DIOXIDE
ABSTRACT OF THE DISCLOSURE
Significant enhancement of titanium dioxide re-covery from a titaniferous ore is achieved by improving the efficiency of the comminution of the ore with the use of polyols of the formula:
R - C -(- R'OH)3 wherein R is alkyl (C1-C4), or hydroxyalkyl (C1-C4) contain-ing up to 3 hydroxy groups, and wherein R' is alkylene (C1-C3).
Description
20~
25,584 IMPROVED GRINDING OF TITANIFE~OUS ORE TO
ENHAN OE ~ECOVERY 0~ TITANIUM DIOXIDE
This invention relates to a method for improving the grinding of titaniferous ores and increasing the amount of recovery of titanium dioxide from said ores.
~ he first step in the sulfuric acid process for reco~ery of titanium dioxide from titaniferous ores, is to grind the ore to a desired particle size; Next the ore is dige~ted with ~ulfuric acid to yield a digestion cake which consists essentially of water 301uble sulfates of titanium and iron, as well as min~r impurities. After dis-~olution of the dige~tion cake in either water or dilute sulfuric acid, the recovery of titanium can be determined by comparing (a) the titanium assay and weight of the ore to (b) the titanium assay and volume of the resulting ~olution.
The sulfuric acid process for preparing titanium di-oxide from titaniferous ores is conducted on a large scale and thus, even a small increase in the recovery of titanium dioxide can be commercially important. For example, for a 25 ton batch of titaniferous ore containing 64.6% titanium dioxide, a change in the titanium dioxide recovery from 84.5%
to 89~ represe~ts a 29% de~rease in unrecovered, or wasted titanium dioxide, and 1400 pounds extra titanium dioxide actually recovered. So, any increase in the efficiency of comminution o~ a titaniferous ore will result in a worth-while saving even though the unit saving may appear small.
Canadian Patent No. 962,003 disclo~es the appli-cation of propane diol to pigmentary titanium dioxide, fol-lowing its preparation by either of the well known sulfuric acid or chloride processes, to improve the dispersibility ~82Q'~
characteristics of the pigment, particularly in paints; and U.S.
Patent No. 3,076,719 describes a treatment of similarly produced titanium dioxide pigment with a polyol of from 4 to 10 carbon atoms which prevents clumping during storage.
U.S. Patent No. 2,822,241 discloses the addition of a clyceride, particularly a monoglyceride, to a titaniferous ore containing organic flotation agents to improve the digestion of the ore in sulfuric acid.
While the prior art discloses use of polyols to improve the qualities of recovered titanium dioxide and the digestion of titaniferous ores, as hereinabove described, the present invention provides as a major object a method whereby the con~minution of tit-aniferous ores may be conducted more efficiently, with the use of certain polyols, so that the recovery of titanium dioxide from said ores upon digestion may be enhanced. Further objects and advantages of the invention will become apparent from the descrip-tion of the invention which ensues.
In accordance with the objects of the present invention, it has been found that certain polyols, when added to an unground titaniferous ore, can increase the efficiency of comminution of the ore.
In one aspect the invention provides a composition which comprises a titaniferous ore and a polyol of the formula:
R- C ( R'OH)3 wherein R is alkyl (Cl-C4), or hydroxyalkyl (Cl-C4) containing up to 3 hydroxy groups, and wherein R' is alkylene (Cl-C3).
i82Q4 - 2a -In another aspect the invention provides a method for improving the comminution of titaniferous ore which comprises ad-ding to the ore a polyol of the above formula.
Preferably, R is alkyl (Cl-C3) and ~' is methylene.
Most preferably, R is ethyl and R' is methylene. The polyols are preferably stable and wettable in concentrated sulfuric acid at ambient temperatures (25C. to 35C.), but tend to be less stable at the digestion reaction temperature. Suitable such compounds include trimethylolpropane, l-nydroxy-2,2-dimethylolpropane;
1-hydroxy-2,2-dimethylolpentane; 1-hydroxy-3,3-diethylolpentane;
1,3-dihydroxy-2,2-dimethylolbutane, and pentaerythritol.
The polyol is added to the titaniferous ore in an , ~, , ..
~8~0 amount effective to lmpro~e the comminution thereof. Gener-ally this am~unt will be from about 0~005% to about 2~ by weight of the ore, desirably from about 0.05% to about 1%, and preferably from about 0.07% to about 0.5%. However, more of the polyol may be added if so desired.
By the introduction of the polyol to the ore either prior to or during comminution, the comminution is rendered more efficient and the ultimate recovery of titanium dioxide from the ore, upon digestion thereof in sulfuric acid, is en-hanced. The polyol appears to act as an anti-caking agent for the ore during comminution, resulting in a more rapid reduction of ore particle size. The smaller particlest in turn, are believed to be better wetted by the sulfuric acid, thereby yielding a higher recovery of titanium dioxide.
In addition to enhancing the comminution of the titaniferous ore, the continued presence of the polyol in the sul~uric acid digestion medium apparently further aug-ments the recovery of titanium dioxide from the ore.
The following exzmples are provided for illustra-ti~e purposes and may include particular features of the in-vention. aow~ever, the examples should not be construed as limiting the invention, many variations of which are pos-sible without departing from the spirit or scope thereof.
All parts and percentages are by weight unless otherwise noted.
Ex~mple 1 In this example, the effecti~e~ess of trimethylol-propane (TMP~ r corresponding to the above polyol formula wherein R is ethyl and R' is methylene, as a grinding aid in the size reduction of a Florida ore from a deposit in Green Cove Springs is shown.
A typical chemical assay of this Florida ore, which is weathered beach sand, re~eals that the titanium dioxide content thereof -is 64.6%.
A 1500 g. sample of the ore was first dried at 110C. to less than 0.2% water and then placed in a gallon ball jar containing 7500 g. of 1 inch steel balls. The ball jar was rotated at 53 rpm for the lengths of time shown in Table I below. At the conclu~ion of the selected grind times, 1~;8~g~4 the ball jar was emptied and the ore particle size determin-ed on a 100 g. sample by sifting in a Tyler Ro-Tap through a bank of sieves ranging from 100 to 3~5 mesh (Tyler - U.S.
Standard) for 30 minutes.
Table 1 demonstrates that for grind times of 30 minutes and 360 minutes, more -325 mesh particles were pro-duced when TMP in an amount of 0.1% was added to the ore.
For this procedure, regular commercially used steel balls, which were not polished, were empIoyed.
TABLE I
Un- Control 0.1% Control 0.1%
ground No TMP No TMP
A~ditive Added Additive A~ded .. .
Grand Time None 30 min. 30 min. 360 min. 360 min.
%~60 mesh 0.04 - - - -%+100 mesh 2.39 1.5 1.6 0.10 +150 mesh 69.0237.~ 38.12 0.20 0.10 ~ +200 mesh 27.0741.4 41.02 2.0 0.30 % +325 mesh 1.32 12.6 9.98 16.4 5.4 % -325 mesh 0.16 7.6 9.28 81.3 94.2 Example 2 Thig example qhows the improvement in titanium di-oxide recovery when a titaniferous ore which was ground us-ing a polyol as a grinding aid is digested with sulfuric acid.
me method used in this example closely approxi-mates the industrial digestion process, so the results received here are representative of results which would be expected on an industrial scale.
Specifically, four separate 1000 g. samples of the titaniferous ore comminuted for equal times as in Example 1, two samples with, and two samples without, the addition o~ 0.1% TMP, were wetted with 98% sulfuric acid for 30 min-utes. Each mixture of ore and sulfuric acid was then heated to 115C. over periods ranging from 19 to 31 minutes, while 60 ml. of water was added to simulate the dilution which oc-curs in the industrial process when high pressure steam ~40 psig) i introduce~ into the mixture. End liquor, i.e., the mother liquor which remains after the titaniferous liquor is hydrolyzed to yield titanium dioxide, was then LJ1t added to achieve the desired ratio of sulfuric acid to basic oxides in the ore. The end li~uor contained about 20% sul-furic acid, and a sufficient quantity was added so that after the valences of all other recoverable sulfatable ore compon-ents had been satisfied, there remained enough sulfuric acidto satisfy between 65 and 80% of the titanium valences with sulfate ions. The samples were digested in the acid solut-ion at temperatures of about 180-190C. for about 2 1/2 hours.
Thereupon, the resulting digestion cakes were dissolved in water to form a titaniferous liqour which was analyzed for titanium dioxide^content, a~d the results compared with the analysis of the original ore, to determine the titanium di-oxide recovery. The determination of recovery càn be made using any well known method, e.g., reduction of the titanium (IV) to titanium (III) with zinc amalgam and titration of the reduced titanium with ferric ammonium sulfate to a thio-cyanate end-point.
It was found upon aAalysis that the average re-covery o~ titanium dioxide from the two samples which had been comminuted with trimethylolpropane was 86.5%. For the two samples comminuted without the use of trimethylolpropane, the average recovery was only 80%.
Example 3 The procedure of Example 1 is repeated, except that the trimethylolpropane i5 replaced by an equal weight amount of l-hydroxy-2,2-dimethylolpropane: 1-hydroxy-2,2-di--methylolpentane; l-hydroxy-3,3-diethylolpentane; 1,3-di--hydroxy-2,2-dimethylolbutane, and pentaerythritol.
Similar improved comminution of the ore is observed.
Example 4 The procedure of Example 1 is repeated, except that trimethylolpropane in amounts equal to 0.005%, 0.05%, 0.5~, 1% and 2% is added to the ore.
Similar improved comminution of the ore is ob-35 served.
25,584 IMPROVED GRINDING OF TITANIFE~OUS ORE TO
ENHAN OE ~ECOVERY 0~ TITANIUM DIOXIDE
This invention relates to a method for improving the grinding of titaniferous ores and increasing the amount of recovery of titanium dioxide from said ores.
~ he first step in the sulfuric acid process for reco~ery of titanium dioxide from titaniferous ores, is to grind the ore to a desired particle size; Next the ore is dige~ted with ~ulfuric acid to yield a digestion cake which consists essentially of water 301uble sulfates of titanium and iron, as well as min~r impurities. After dis-~olution of the dige~tion cake in either water or dilute sulfuric acid, the recovery of titanium can be determined by comparing (a) the titanium assay and weight of the ore to (b) the titanium assay and volume of the resulting ~olution.
The sulfuric acid process for preparing titanium di-oxide from titaniferous ores is conducted on a large scale and thus, even a small increase in the recovery of titanium dioxide can be commercially important. For example, for a 25 ton batch of titaniferous ore containing 64.6% titanium dioxide, a change in the titanium dioxide recovery from 84.5%
to 89~ represe~ts a 29% de~rease in unrecovered, or wasted titanium dioxide, and 1400 pounds extra titanium dioxide actually recovered. So, any increase in the efficiency of comminution o~ a titaniferous ore will result in a worth-while saving even though the unit saving may appear small.
Canadian Patent No. 962,003 disclo~es the appli-cation of propane diol to pigmentary titanium dioxide, fol-lowing its preparation by either of the well known sulfuric acid or chloride processes, to improve the dispersibility ~82Q'~
characteristics of the pigment, particularly in paints; and U.S.
Patent No. 3,076,719 describes a treatment of similarly produced titanium dioxide pigment with a polyol of from 4 to 10 carbon atoms which prevents clumping during storage.
U.S. Patent No. 2,822,241 discloses the addition of a clyceride, particularly a monoglyceride, to a titaniferous ore containing organic flotation agents to improve the digestion of the ore in sulfuric acid.
While the prior art discloses use of polyols to improve the qualities of recovered titanium dioxide and the digestion of titaniferous ores, as hereinabove described, the present invention provides as a major object a method whereby the con~minution of tit-aniferous ores may be conducted more efficiently, with the use of certain polyols, so that the recovery of titanium dioxide from said ores upon digestion may be enhanced. Further objects and advantages of the invention will become apparent from the descrip-tion of the invention which ensues.
In accordance with the objects of the present invention, it has been found that certain polyols, when added to an unground titaniferous ore, can increase the efficiency of comminution of the ore.
In one aspect the invention provides a composition which comprises a titaniferous ore and a polyol of the formula:
R- C ( R'OH)3 wherein R is alkyl (Cl-C4), or hydroxyalkyl (Cl-C4) containing up to 3 hydroxy groups, and wherein R' is alkylene (Cl-C3).
i82Q4 - 2a -In another aspect the invention provides a method for improving the comminution of titaniferous ore which comprises ad-ding to the ore a polyol of the above formula.
Preferably, R is alkyl (Cl-C3) and ~' is methylene.
Most preferably, R is ethyl and R' is methylene. The polyols are preferably stable and wettable in concentrated sulfuric acid at ambient temperatures (25C. to 35C.), but tend to be less stable at the digestion reaction temperature. Suitable such compounds include trimethylolpropane, l-nydroxy-2,2-dimethylolpropane;
1-hydroxy-2,2-dimethylolpentane; 1-hydroxy-3,3-diethylolpentane;
1,3-dihydroxy-2,2-dimethylolbutane, and pentaerythritol.
The polyol is added to the titaniferous ore in an , ~, , ..
~8~0 amount effective to lmpro~e the comminution thereof. Gener-ally this am~unt will be from about 0~005% to about 2~ by weight of the ore, desirably from about 0.05% to about 1%, and preferably from about 0.07% to about 0.5%. However, more of the polyol may be added if so desired.
By the introduction of the polyol to the ore either prior to or during comminution, the comminution is rendered more efficient and the ultimate recovery of titanium dioxide from the ore, upon digestion thereof in sulfuric acid, is en-hanced. The polyol appears to act as an anti-caking agent for the ore during comminution, resulting in a more rapid reduction of ore particle size. The smaller particlest in turn, are believed to be better wetted by the sulfuric acid, thereby yielding a higher recovery of titanium dioxide.
In addition to enhancing the comminution of the titaniferous ore, the continued presence of the polyol in the sul~uric acid digestion medium apparently further aug-ments the recovery of titanium dioxide from the ore.
The following exzmples are provided for illustra-ti~e purposes and may include particular features of the in-vention. aow~ever, the examples should not be construed as limiting the invention, many variations of which are pos-sible without departing from the spirit or scope thereof.
All parts and percentages are by weight unless otherwise noted.
Ex~mple 1 In this example, the effecti~e~ess of trimethylol-propane (TMP~ r corresponding to the above polyol formula wherein R is ethyl and R' is methylene, as a grinding aid in the size reduction of a Florida ore from a deposit in Green Cove Springs is shown.
A typical chemical assay of this Florida ore, which is weathered beach sand, re~eals that the titanium dioxide content thereof -is 64.6%.
A 1500 g. sample of the ore was first dried at 110C. to less than 0.2% water and then placed in a gallon ball jar containing 7500 g. of 1 inch steel balls. The ball jar was rotated at 53 rpm for the lengths of time shown in Table I below. At the conclu~ion of the selected grind times, 1~;8~g~4 the ball jar was emptied and the ore particle size determin-ed on a 100 g. sample by sifting in a Tyler Ro-Tap through a bank of sieves ranging from 100 to 3~5 mesh (Tyler - U.S.
Standard) for 30 minutes.
Table 1 demonstrates that for grind times of 30 minutes and 360 minutes, more -325 mesh particles were pro-duced when TMP in an amount of 0.1% was added to the ore.
For this procedure, regular commercially used steel balls, which were not polished, were empIoyed.
TABLE I
Un- Control 0.1% Control 0.1%
ground No TMP No TMP
A~ditive Added Additive A~ded .. .
Grand Time None 30 min. 30 min. 360 min. 360 min.
%~60 mesh 0.04 - - - -%+100 mesh 2.39 1.5 1.6 0.10 +150 mesh 69.0237.~ 38.12 0.20 0.10 ~ +200 mesh 27.0741.4 41.02 2.0 0.30 % +325 mesh 1.32 12.6 9.98 16.4 5.4 % -325 mesh 0.16 7.6 9.28 81.3 94.2 Example 2 Thig example qhows the improvement in titanium di-oxide recovery when a titaniferous ore which was ground us-ing a polyol as a grinding aid is digested with sulfuric acid.
me method used in this example closely approxi-mates the industrial digestion process, so the results received here are representative of results which would be expected on an industrial scale.
Specifically, four separate 1000 g. samples of the titaniferous ore comminuted for equal times as in Example 1, two samples with, and two samples without, the addition o~ 0.1% TMP, were wetted with 98% sulfuric acid for 30 min-utes. Each mixture of ore and sulfuric acid was then heated to 115C. over periods ranging from 19 to 31 minutes, while 60 ml. of water was added to simulate the dilution which oc-curs in the industrial process when high pressure steam ~40 psig) i introduce~ into the mixture. End liquor, i.e., the mother liquor which remains after the titaniferous liquor is hydrolyzed to yield titanium dioxide, was then LJ1t added to achieve the desired ratio of sulfuric acid to basic oxides in the ore. The end li~uor contained about 20% sul-furic acid, and a sufficient quantity was added so that after the valences of all other recoverable sulfatable ore compon-ents had been satisfied, there remained enough sulfuric acidto satisfy between 65 and 80% of the titanium valences with sulfate ions. The samples were digested in the acid solut-ion at temperatures of about 180-190C. for about 2 1/2 hours.
Thereupon, the resulting digestion cakes were dissolved in water to form a titaniferous liqour which was analyzed for titanium dioxide^content, a~d the results compared with the analysis of the original ore, to determine the titanium di-oxide recovery. The determination of recovery càn be made using any well known method, e.g., reduction of the titanium (IV) to titanium (III) with zinc amalgam and titration of the reduced titanium with ferric ammonium sulfate to a thio-cyanate end-point.
It was found upon aAalysis that the average re-covery o~ titanium dioxide from the two samples which had been comminuted with trimethylolpropane was 86.5%. For the two samples comminuted without the use of trimethylolpropane, the average recovery was only 80%.
Example 3 The procedure of Example 1 is repeated, except that the trimethylolpropane i5 replaced by an equal weight amount of l-hydroxy-2,2-dimethylolpropane: 1-hydroxy-2,2-di--methylolpentane; l-hydroxy-3,3-diethylolpentane; 1,3-di--hydroxy-2,2-dimethylolbutane, and pentaerythritol.
Similar improved comminution of the ore is observed.
Example 4 The procedure of Example 1 is repeated, except that trimethylolpropane in amounts equal to 0.005%, 0.05%, 0.5~, 1% and 2% is added to the ore.
Similar improved comminution of the ore is ob-35 served.
Claims (10)
1. A composition which comprises a titaniferous ore and a polyol of the formula:
R-C(- R'OH)3 wherein R is alkyl (C1-C4), or hydroxyalkyl (C1-C4) having up to three hydroxy groups, and wherein R' is alkylene (C1-C3).
R-C(- R'OH)3 wherein R is alkyl (C1-C4), or hydroxyalkyl (C1-C4) having up to three hydroxy groups, and wherein R' is alkylene (C1-C3).
2. The composition of Claim 1 wherein R is alkyl (C1-C4) and R' is methylene.
3. The composition of Claim 1 wherein the polyol is trimethylolpropane.
4. The composition of Claim 1 wherein the polyol is present in an amount effective to reduce the particle size of the ore as a result of comminution.
5. The composition of Claim 1 wherein the polyol is present in an amount equal to from about 0.005% to about 2%
by weight of the ore.
by weight of the ore.
6. A method for improving the comminution of a titan-iferous ore which comprises adding to said ore a polyol having the formula:
R-C(-R'OH)3 wherein R is alkyl (C1-C4) or hydroxyalkyl (C1-C4) containing up to three hydroxy groups and wherein R' is alkylene (C1-C3), in an amount effective to reduce the particle size of the ore as a result of the comminution.
R-C(-R'OH)3 wherein R is alkyl (C1-C4) or hydroxyalkyl (C1-C4) containing up to three hydroxy groups and wherein R' is alkylene (C1-C3), in an amount effective to reduce the particle size of the ore as a result of the comminution.
7. The method of Claim 6 wherein R of the formula R-C-(R'OH3) is alkyl (C1-C4) and R' of said formula is methylene.
8. The method of Claim 6 wherein the polyol is trimethylolpropane.
9. The method of Claim 6 wherein the polyol is present in an amount equal to from about 0.005% to about 2% by weight of the ore.
10. The method of Claim 6 wherein the polyol is present in an amount equal to from about 0.05% to about 1% by weight of the ore.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000396079A CA1168204A (en) | 1982-02-11 | 1982-02-11 | Grinding of titaniferous ores to enhance recovery of titanium dioxide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000396079A CA1168204A (en) | 1982-02-11 | 1982-02-11 | Grinding of titaniferous ores to enhance recovery of titanium dioxide |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168204A true CA1168204A (en) | 1984-05-29 |
Family
ID=4122034
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000396079A Expired CA1168204A (en) | 1982-02-11 | 1982-02-11 | Grinding of titaniferous ores to enhance recovery of titanium dioxide |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1168204A (en) |
-
1982
- 1982-02-11 CA CA000396079A patent/CA1168204A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1220345A (en) | Process for the recovery of noble metals from ores | |
| CN102220488A (en) | Method for separating rare earth from phosphate ore | |
| US4134737A (en) | Process for producing high-purity coal | |
| CN101736404A (en) | Co-production method of calcium sulfate whisker and phosphoric acid | |
| US4489043A (en) | Manufacture of manganous sulfate solutions | |
| CN104261473B (en) | A kind of preparation method of Vanadium Pentoxide in FLAKES | |
| CN103193272B (en) | Method for preparing ammonium paratungstate | |
| CN109354071A (en) | A method of LITHIUM BATTERY manganese sulfate is produced using manganese tailing and Titanium white waste sulfuric acid | |
| CN111215247B (en) | Inhibitor for high-calcium fluorite direct flotation and flotation method | |
| US4485073A (en) | Process of producing manganese sulfate solutions | |
| CN113184821B (en) | Method for preparing ferric phosphate from iron-containing slag | |
| CA1168204A (en) | Grinding of titaniferous ores to enhance recovery of titanium dioxide | |
| US3667906A (en) | Method for producing manganese dioxide containing less potassium | |
| US4483828A (en) | Method of producing manganese sulfate solutions of improved purity | |
| US4321152A (en) | Grinding of titaniferous ores to enhance recovery of titanium dioxide | |
| CN101863472B (en) | Method for recovering tungsten carbide from discarded hard alloy | |
| US4154799A (en) | Dicalcium phosphate manufacture | |
| EP0085728B1 (en) | Improved grinding of titaniferous ores to enhance recovery of titanium dioxide | |
| CN106882839B (en) | Method for comprehensively utilizing titanium white waste acid | |
| US3939249A (en) | Purification of talc | |
| EP0420525A2 (en) | Recycling metal containing compositions | |
| EP1034136B1 (en) | Treatment of a solution containing iron salts | |
| US5068093A (en) | Method for producing titanium dioxide | |
| CN109321747B (en) | Method for leaching manganese concentrate from low-grade calciummanganese ore and regenerating leaching medium | |
| CN101979341B (en) | Vanadium and chromium heavy metal ions-containing leaching ore waste water treatment method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |