CA2240082C - Process for silica and magnesium salts production from tailings coming from asbestos mining - Google Patents
Process for silica and magnesium salts production from tailings coming from asbestos mining Download PDFInfo
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- CA2240082C CA2240082C CA 2240082 CA2240082A CA2240082C CA 2240082 C CA2240082 C CA 2240082C CA 2240082 CA2240082 CA 2240082 CA 2240082 A CA2240082 A CA 2240082A CA 2240082 C CA2240082 C CA 2240082C
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
- B01J20/28057—Surface area, e.g. B.E.T specific surface area
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
- B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/126—Preparation of silica of undetermined type
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/26—Magnesium halides
- C01F5/30—Chlorides
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/40—Magnesium sulfates
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
- C22B26/20—Obtaining alkaline earth metals or magnesium
- C22B26/22—Obtaining magnesium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/006—Wet processes
- C22B7/007—Wet processes by acid leaching
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- General Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Analytical Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Processing Of Solid Wastes (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
There are numerous technologies to extract magnesium from tailings piles coming from asbestos mining. In the invention we have found that silica which is a component of the asbestos fibers with magnesium oxide can be extracted with magnesium in combining extraction of the asbestos fibers by flotation (wet-milling technologies), the treatment of the water-soaked fibers with an acid and, after reaction the separation of the solid silica from the magnesium salt solution which can then process. The silica shows a great surface area (400 -450 m2/g) which makes it a valuable product with many industrial applications. The extraction of these two products gives a good profitability to this new tailings processing technology.
Description
PROCESS FOR SILICA AND MAGNESIUM SALTS PRODUCTION
FROM TAILINGS COMING FROM ASBESTOS MINING
The invention relates, to a process which produces silica with great surface area and magnesium salts from asbestos fibers.
The asbestos fibers have been used during a long time for insulation of buildings and the reinforcement of different materials.
Due to toxicological problems, this use diminishes.
Today the stock piles of tailings which are the ore residue after dry mill extractions of asbestos fibers remain in the mine sites.
They are generally made with crushed serpentine rocks with residual asbestos fibers (mainly magnesium silicates) in sufficient quantity to be considered as a potential source of magnesium.
Different technologies have been proposed in which the tailings are treated with various chemicals. The most significant technologies which can give magnesium salts and magnesium oxide or magnesium summarized below, use:
- chiorhydric acid leaching (Magnola Process, Celik. C. and al, C.A.
127:193389, Proc. Int. Magnesium Conf., London, 1997; Leao. V.A. and al, C. A. 127: 68828, E.P.D. Congr. Proc. Sess. symp., 1997, 511-527) - sulfuric acid leaching (Hu W. and al, C. A. 120: 195.218, Chinese patent 92-110146; Chen. J. and al C.A. 119: 30998, Kuang Chan Zhonghe Liyong, 1992, (3), 13-17; Cui. G. and al, C.A. 116: 197025, Feijinshukuang 1991, (3), 32-39; Timashev. V.V. and al, C.A. 97:
149618, Mosk. Khim. Tekhnol. lust., 1981, (18), 109-113) - chlorhydric and sulfuric acid leaching (Katahira. A. V., C.A. 127:37438, Hydrometallurgy, 1997, (45), 323-331) - alkali treatment with sodium carbonates (Lalancette et al, C. A. 102:
9035, US patent no. 4478 796) or with ammonium bicarbonate (Lei. S.
and al, C.A. 121: 233933, Wuhan Gongye Daxue Xuebao, 1994, (16) 65-68) - ferrite precipitation and magnetic separations (Yang K and al., C. A.
122: 141438, EPD Congress, Proc. Symp., 1996, 363-373) - plasma furnace process (Magram process, Chapman. C. D. and al, C.
A. 125: 91902, Recycl. Mat. Eng. Mater. Inter. Symp. (3), 1995) These processes can produce only magnesium under salt, oxide or metal form. The remaining silica, which comes from the original magnesium silicates, mixed with the residue, cannot be economically separated and is deposed with it.
This is unfortunate is this silica has, on account of information coming from toxicological studies on the asbestos fibers, a great surface area (Holmes et al, Nature, 1967, (215), 441; Toman K and al, Acta Crystallograph, sect A, 1968, (24), 276; Yada K. Acta Crystallograph, Sect A, 1971, (27), 659;
Jaurand et al, C. A. 85: 154687, rev. Fr. Mal. Respir., 1976 (4), 111.) We have found that these disadvantages can be overcome, in order to produce from the tailings, silica with great surface area and magnesium salts in combining the extraction of the asbestos fibers by flotation (wet-milling/wet processing technology), the treatment of the water-soaked fibers with an acid and, after reaction, the solid/liquid separation of the solid particles of silica from the magnesium salt solution.
The innovation arises that the surprising facts of science: a silica with a great surface area (100 mz/g to 450 m2/g) can be produced and separated from the magnesium saft solution in short duration times, in conditions easy to scale up.
It seems it is the first time that absorbent silicas from natural mineral fibers can be produced at large scale at a price that can compete with synthetic precipitated silicas produced by acid precipitation of alkali silicates which have a huge market in chemicals, catalysts, polymers, feedstuff industry, fire extinguishing substances, inks, paper industry, adhesives, etc.
As magnesium or magnesium oxide can be extracted easily from the magnesium salt solutions using known technologies, the tailings treated with the present process lead to two very valuable products.
The process of the invention can be implemented with asbestos tailings produced by dry-mill operations which comprises a flotation extraction of asbestos fibers. In a wet mill at industrial scale the plant is fed from the tailings piles with a slurry (=30% solids) by a pipeline. The wet mill consists of large decanters and circuits with screens, cyclones, pumps and classifiers.
The classification is very rough in comparison with the production of fibers for conventional uses, because the fiber length and the fiber thickness have .not direct relationship with the surface area of the silica lattice. The water soaked fibers are then treated with an acid at the required concentration.
FROM TAILINGS COMING FROM ASBESTOS MINING
The invention relates, to a process which produces silica with great surface area and magnesium salts from asbestos fibers.
The asbestos fibers have been used during a long time for insulation of buildings and the reinforcement of different materials.
Due to toxicological problems, this use diminishes.
Today the stock piles of tailings which are the ore residue after dry mill extractions of asbestos fibers remain in the mine sites.
They are generally made with crushed serpentine rocks with residual asbestos fibers (mainly magnesium silicates) in sufficient quantity to be considered as a potential source of magnesium.
Different technologies have been proposed in which the tailings are treated with various chemicals. The most significant technologies which can give magnesium salts and magnesium oxide or magnesium summarized below, use:
- chiorhydric acid leaching (Magnola Process, Celik. C. and al, C.A.
127:193389, Proc. Int. Magnesium Conf., London, 1997; Leao. V.A. and al, C. A. 127: 68828, E.P.D. Congr. Proc. Sess. symp., 1997, 511-527) - sulfuric acid leaching (Hu W. and al, C. A. 120: 195.218, Chinese patent 92-110146; Chen. J. and al C.A. 119: 30998, Kuang Chan Zhonghe Liyong, 1992, (3), 13-17; Cui. G. and al, C.A. 116: 197025, Feijinshukuang 1991, (3), 32-39; Timashev. V.V. and al, C.A. 97:
149618, Mosk. Khim. Tekhnol. lust., 1981, (18), 109-113) - chlorhydric and sulfuric acid leaching (Katahira. A. V., C.A. 127:37438, Hydrometallurgy, 1997, (45), 323-331) - alkali treatment with sodium carbonates (Lalancette et al, C. A. 102:
9035, US patent no. 4478 796) or with ammonium bicarbonate (Lei. S.
and al, C.A. 121: 233933, Wuhan Gongye Daxue Xuebao, 1994, (16) 65-68) - ferrite precipitation and magnetic separations (Yang K and al., C. A.
122: 141438, EPD Congress, Proc. Symp., 1996, 363-373) - plasma furnace process (Magram process, Chapman. C. D. and al, C.
A. 125: 91902, Recycl. Mat. Eng. Mater. Inter. Symp. (3), 1995) These processes can produce only magnesium under salt, oxide or metal form. The remaining silica, which comes from the original magnesium silicates, mixed with the residue, cannot be economically separated and is deposed with it.
This is unfortunate is this silica has, on account of information coming from toxicological studies on the asbestos fibers, a great surface area (Holmes et al, Nature, 1967, (215), 441; Toman K and al, Acta Crystallograph, sect A, 1968, (24), 276; Yada K. Acta Crystallograph, Sect A, 1971, (27), 659;
Jaurand et al, C. A. 85: 154687, rev. Fr. Mal. Respir., 1976 (4), 111.) We have found that these disadvantages can be overcome, in order to produce from the tailings, silica with great surface area and magnesium salts in combining the extraction of the asbestos fibers by flotation (wet-milling/wet processing technology), the treatment of the water-soaked fibers with an acid and, after reaction, the solid/liquid separation of the solid particles of silica from the magnesium salt solution.
The innovation arises that the surprising facts of science: a silica with a great surface area (100 mz/g to 450 m2/g) can be produced and separated from the magnesium saft solution in short duration times, in conditions easy to scale up.
It seems it is the first time that absorbent silicas from natural mineral fibers can be produced at large scale at a price that can compete with synthetic precipitated silicas produced by acid precipitation of alkali silicates which have a huge market in chemicals, catalysts, polymers, feedstuff industry, fire extinguishing substances, inks, paper industry, adhesives, etc.
As magnesium or magnesium oxide can be extracted easily from the magnesium salt solutions using known technologies, the tailings treated with the present process lead to two very valuable products.
The process of the invention can be implemented with asbestos tailings produced by dry-mill operations which comprises a flotation extraction of asbestos fibers. In a wet mill at industrial scale the plant is fed from the tailings piles with a slurry (=30% solids) by a pipeline. The wet mill consists of large decanters and circuits with screens, cyclones, pumps and classifiers.
The classification is very rough in comparison with the production of fibers for conventional uses, because the fiber length and the fiber thickness have .not direct relationship with the surface area of the silica lattice. The water soaked fibers are then treated with an acid at the required concentration.
These two modifications reduce greatly the operating cost of the wet mill which is of great value for the entire process.
The separation of the solid silica after reaction from the magnesium salt solution is easy like magnesium recovery under salt or oxide form.
The asbestos fibers are mainly chrysotile which is a magnesium silicate of general formula : Mg3 (Si2 05 (OH)4]
The process of the innovation can be implemented with mineral acid or organic acid with a solid/liquid separation made by filtration.
A favourite implementation uses mineral acid treatment of chrysotile fibers followed by a solid/liquid separation. The solid residue obtained is then treated with an organic acid solution to give high grade absorbent silica with a great surface area.
Another favourite implementation is the washing of the solid residue obtained after each acid treatment with an acid solution of the same origin before washing with water in order to avoid any kind of salt precipitation in the silica lattice.
Very good results have been obtained when the mineral acid is chlorhydric acid and the organic acid is oxalic acid.
A favourite implementation of the process with two acid treatments with chlorhydric acid and oxalic acid leads to the recovery of 99.1 % of magnesium with magnesium salt solution tifrated with conventional atomic absorption method and the separation by filtration of a silica which shows a surface area of 440 mZ/g.
The magnesium can be recovered under ionic form from the magnesium salt solution among others by evaporation of the liquid solution or fixation on ion exchange resin in order to have after regeneration a pure product. The acid solution obtained after evaporation or regeneration can be recycled for the treatment of chrysotile fibers. This process which reduces waste and conserves resources is a green one.
These silicas of great surface area have been obtained by an original way totally different from the common one using the precipitation of alkali silicates solution with a mineral acid.
We claim the quality of new products for the silicas of great surface area described below.
The invention is illustrated by the following examples:
EXAMPLE No. 1:
L of a 1 N chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 4 h at 75 C and then poured on a filter.
The solid residue is washed with 3 L of IN chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 84.2% of magnesium has been extracted.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 360mZ/g.
EXAMPLE No. 2:
L of a IN chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 4 h at 75 C and then poured on a filter.
The solid residue is washed with 3 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 78.7% of magnesium has been extracted.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 325m2/g.
EXAMPLE No. 3:
L of a 2N chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
1.2 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundiand, Canada are added.
The mixture is stirred during 4 h at 80 C and then poured on a filter.
The solid residue is washed with 3 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 83.5% of magnesium has been extracted.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 350m2/g.
EXAMPLE No. 4:
12 L of a 1 N oxalic acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.5 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 24 h at 70 C and then poured on a filter.
The solid residue is washed with 2 L of 1 N oxalic acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 87% of magnesium has been extracted.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 380m2/g.
EXAMPLE No. 5:
L of a IN chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 4 h at 70 C and then poured on a filter.
The solid residue is washed with 2 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 82.2% of magnesium has been extracted.
The solid residue is then added to a 10 L of a IN oxalic acid solution placed in the same 25 I equipped reactor described below.
The mixture is stirred 3 H at 80 C. and filtered. The silica is washed with 2 I of 1 N oxalic acid solution and water up to neutrality.
The magnesium extracted is titrated with the conventional atomic absorption method. 16.9% of magnesium is recovered.
The total amount of magnesium recovered during the two stages is of 99.1%.
The silica shows a surface area of 440 m2/g measured by the conventional B.E.T. nitrogen adsorption method.
EXAMPLE No. 6:
L of a 2N chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 8 h at 75 C and then poured on a filter.
The solid residue is washed with 3 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 98.9% of magnesium has been extracted.
The aqueous chlorhydric acid solution is evaporated under vacuum allowing the recovery of the magnesium chloride under solid form.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 430m2/g.
EXAMPLE No. 7:
10 L of a 1.5N chiorhydric acid solution are placed in a 25 L
conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 8 h at 75 C and then poured on a filter.
The solid residue is washed with 3 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 98.2% of magnesium has been extracted.
The acid aqueous solution of magnesium chloride is percolated on a glass column fitted at the bottom with a glass porous filter and a tap (diameter: 0.1 m, height: 1 m) where 9 liters of polystyrenic sulfonic onic exchange resin (exchange capacity: 0.5 mole H+/L) has been placed.
The magnesium ions are totally retained on the polymer and separated from the chlorhydric acid solution which can be recycled for the treatment of chrysotile fibers.
The magnesium is then recovered under solid magnesium sulfate after percolation of a 2N sulfuric acid solution and evaporation of the magnesium sulfate solution obtained under vacuum.
The ion exchange is regenerated and can be used for another magnesium ion extraction.
The surface area of the silica measured with the conventional B.E.T.
nitrogen method is of 410 m2g.
The separation of the solid silica after reaction from the magnesium salt solution is easy like magnesium recovery under salt or oxide form.
The asbestos fibers are mainly chrysotile which is a magnesium silicate of general formula : Mg3 (Si2 05 (OH)4]
The process of the innovation can be implemented with mineral acid or organic acid with a solid/liquid separation made by filtration.
A favourite implementation uses mineral acid treatment of chrysotile fibers followed by a solid/liquid separation. The solid residue obtained is then treated with an organic acid solution to give high grade absorbent silica with a great surface area.
Another favourite implementation is the washing of the solid residue obtained after each acid treatment with an acid solution of the same origin before washing with water in order to avoid any kind of salt precipitation in the silica lattice.
Very good results have been obtained when the mineral acid is chlorhydric acid and the organic acid is oxalic acid.
A favourite implementation of the process with two acid treatments with chlorhydric acid and oxalic acid leads to the recovery of 99.1 % of magnesium with magnesium salt solution tifrated with conventional atomic absorption method and the separation by filtration of a silica which shows a surface area of 440 mZ/g.
The magnesium can be recovered under ionic form from the magnesium salt solution among others by evaporation of the liquid solution or fixation on ion exchange resin in order to have after regeneration a pure product. The acid solution obtained after evaporation or regeneration can be recycled for the treatment of chrysotile fibers. This process which reduces waste and conserves resources is a green one.
These silicas of great surface area have been obtained by an original way totally different from the common one using the precipitation of alkali silicates solution with a mineral acid.
We claim the quality of new products for the silicas of great surface area described below.
The invention is illustrated by the following examples:
EXAMPLE No. 1:
L of a 1 N chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 4 h at 75 C and then poured on a filter.
The solid residue is washed with 3 L of IN chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 84.2% of magnesium has been extracted.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 360mZ/g.
EXAMPLE No. 2:
L of a IN chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 4 h at 75 C and then poured on a filter.
The solid residue is washed with 3 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 78.7% of magnesium has been extracted.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 325m2/g.
EXAMPLE No. 3:
L of a 2N chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
1.2 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundiand, Canada are added.
The mixture is stirred during 4 h at 80 C and then poured on a filter.
The solid residue is washed with 3 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 83.5% of magnesium has been extracted.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 350m2/g.
EXAMPLE No. 4:
12 L of a 1 N oxalic acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.5 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 24 h at 70 C and then poured on a filter.
The solid residue is washed with 2 L of 1 N oxalic acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 87% of magnesium has been extracted.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 380m2/g.
EXAMPLE No. 5:
L of a IN chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 4 h at 70 C and then poured on a filter.
The solid residue is washed with 2 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 82.2% of magnesium has been extracted.
The solid residue is then added to a 10 L of a IN oxalic acid solution placed in the same 25 I equipped reactor described below.
The mixture is stirred 3 H at 80 C. and filtered. The silica is washed with 2 I of 1 N oxalic acid solution and water up to neutrality.
The magnesium extracted is titrated with the conventional atomic absorption method. 16.9% of magnesium is recovered.
The total amount of magnesium recovered during the two stages is of 99.1%.
The silica shows a surface area of 440 m2/g measured by the conventional B.E.T. nitrogen adsorption method.
EXAMPLE No. 6:
L of a 2N chlorhydric acid solution are placed in a 25 L conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 8 h at 75 C and then poured on a filter.
The solid residue is washed with 3 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 98.9% of magnesium has been extracted.
The aqueous chlorhydric acid solution is evaporated under vacuum allowing the recovery of the magnesium chloride under solid form.
The surface area of the silica measured with the conventional B.E.T.
nitrogen adsorption method, is of 430m2/g.
EXAMPLE No. 7:
10 L of a 1.5N chiorhydric acid solution are placed in a 25 L
conventional glass chemical reactor fitted with a feeding device, a mechanical stirrer and a thermometer.
0.4 kg (dry weight) of chrysotile type fibers water-soaked coming from the tailings pile and process in the wet-milling facilities of the Baie Verte Asbestos Mine - Baie Verte, Newfoundland, Canada are added.
The mixture is stirred during 8 h at 75 C and then poured on a filter.
The solid residue is washed with 3 L of 1 N chlorhydric acid solution and washed up to neutrality.
The magnesium is titrated in the acid aqueous solution using conventional atomic absorption method. 98.2% of magnesium has been extracted.
The acid aqueous solution of magnesium chloride is percolated on a glass column fitted at the bottom with a glass porous filter and a tap (diameter: 0.1 m, height: 1 m) where 9 liters of polystyrenic sulfonic onic exchange resin (exchange capacity: 0.5 mole H+/L) has been placed.
The magnesium ions are totally retained on the polymer and separated from the chlorhydric acid solution which can be recycled for the treatment of chrysotile fibers.
The magnesium is then recovered under solid magnesium sulfate after percolation of a 2N sulfuric acid solution and evaporation of the magnesium sulfate solution obtained under vacuum.
The ion exchange is regenerated and can be used for another magnesium ion extraction.
The surface area of the silica measured with the conventional B.E.T.
nitrogen method is of 410 m2g.
Claims (13)
1. A process to treat tailings coming from asbestos dry-milling operations which comprises:
- a wet processing extraction of asbestos fibers;
- a treatment of water-soaked fibers with an acid;
- a separation of solid silica obtained after reaction from magnesium salt solution; and - a separation of magnesium salt from the solution.
- a wet processing extraction of asbestos fibers;
- a treatment of water-soaked fibers with an acid;
- a separation of solid silica obtained after reaction from magnesium salt solution; and - a separation of magnesium salt from the solution.
2. The process as defined in claim 1 in which the asbestos fibers comprise chrysotile fibers.
3. The process as defined in claim 1 or 2 in which the acid used is of mineral origin.
4. The process as defined in claim 1 or 2 in which the acid used is of organic origin.
5. The process as defined in claim 1, 2, 3 or 4 in which the solid/liquid separation is made by filtration.
6. The process as defined in claim 1 or 3 wherein the acid is mineral acid, the asbestos fibers comprise chrysotile fibers, and the solid/liquid separation is followed by a step of treating a resulting solid silica with an organic acid solution to produce high grade absorbent silica.
7. The process as defined in claim 1, 2, 3, 4 or 5 in which a solid silica obtained after said acid treatment and said separation from the magnesium salt solution, is washed with an acid solution of the same origin before being washed with water.
8. The process as defined in claim 3 or 6 in which the mineral acid is chlorhydric acid.
9. The process as defined in claim 4 or 6 in which the organic acid is oxalic acid.
10. The process as defined in claim 1, 2, 3, 4, 5, 6, 7, 8 or 9 in which the magnesium salt solution is percolated on an ion exchange resin in order to extract the magnesium under ionic form from the solution.
11. The process as defined in claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 wherein the acid is chlorhydric acid, and in which a chlorhydric acid solution is evaporated in order to recover the magnesium salt comprising magnesium chloride, under solid and dry form.
12. The process as defined in claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11 in which the acid solution obtained after magnesium salt separation is recycled for the treatment of asbestos fibers.
13. A process to treat tailings coming from asbestos dry-milling operations which comprises:
- a wet processing extraction of asbestos fibers;
- a treatment of water-soaked fibers with an acid;
- a separation of solid silica obtained after reaction from magnesium salt solution, wherein the solid silica is absorbed in silica with a surface area between 350 m2/g to 450 m2/g; and - a separation of magnesium salt from the solution.
- a wet processing extraction of asbestos fibers;
- a treatment of water-soaked fibers with an acid;
- a separation of solid silica obtained after reaction from magnesium salt solution, wherein the solid silica is absorbed in silica with a surface area between 350 m2/g to 450 m2/g; and - a separation of magnesium salt from the solution.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2240082 CA2240082C (en) | 1998-07-27 | 1998-07-27 | Process for silica and magnesium salts production from tailings coming from asbestos mining |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2240082 CA2240082C (en) | 1998-07-27 | 1998-07-27 | Process for silica and magnesium salts production from tailings coming from asbestos mining |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2240082A1 CA2240082A1 (en) | 2000-01-27 |
| CA2240082C true CA2240082C (en) | 2010-05-11 |
Family
ID=29275863
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2240082 Expired - Fee Related CA2240082C (en) | 1998-07-27 | 1998-07-27 | Process for silica and magnesium salts production from tailings coming from asbestos mining |
Country Status (1)
| Country | Link |
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| CA (1) | CA2240082C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2515735C1 (en) * | 2013-01-29 | 2014-05-20 | Федеральное государственное унитарное предприятие "Горно-химический комбинат" | Method to extract metals from silicate slags |
| RU2568796C1 (en) * | 2014-06-03 | 2015-11-20 | Федеральное государственное бюджетное учреждение науки Институт химии и технологии редких элементов и минерального сырья им. И.В. Тананаева Кольского научного центра Российской академии наук (ИХТРЭМС КНЦ РАН) | Slag break-down process |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104891951B (en) * | 2015-05-19 | 2017-04-12 | 河北工程大学 | A method of extracting a silicon-magnesium-aluminum composite insulating material from asbestos tailings |
| FR3125722B1 (en) | 2021-07-30 | 2023-07-07 | Valame | METHOD FOR TREATMENT OF A SOLID MATERIAL CONTAINING ASBESTOS |
-
1998
- 1998-07-27 CA CA 2240082 patent/CA2240082C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2515735C1 (en) * | 2013-01-29 | 2014-05-20 | Федеральное государственное унитарное предприятие "Горно-химический комбинат" | Method to extract metals from silicate slags |
| RU2568796C1 (en) * | 2014-06-03 | 2015-11-20 | Федеральное государственное бюджетное учреждение науки Институт химии и технологии редких элементов и минерального сырья им. И.В. Тананаева Кольского научного центра Российской академии наук (ИХТРЭМС КНЦ РАН) | Slag break-down process |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2240082A1 (en) | 2000-01-27 |
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