CA1162747A - Process for the solidification of tailings produced by the processing of hard rock ore - Google Patents
Process for the solidification of tailings produced by the processing of hard rock oreInfo
- Publication number
- CA1162747A CA1162747A CA000354572A CA354572A CA1162747A CA 1162747 A CA1162747 A CA 1162747A CA 000354572 A CA000354572 A CA 000354572A CA 354572 A CA354572 A CA 354572A CA 1162747 A CA1162747 A CA 1162747A
- Authority
- CA
- Canada
- Prior art keywords
- tailings
- hydroxide
- range
- processing
- earth metal
- 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
Classifications
-
- 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
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for the solidification of tailings created by the processing of hard rock ore. The process comprises first adding sulphuric acid to the tailings to condition them, followed by reacting the mixture with an alkaline earth metal oxide or hydroxide to raise the pH above 10Ø After a curing period, the tailings become a rock-like physically stable material.
A process for the solidification of tailings created by the processing of hard rock ore. The process comprises first adding sulphuric acid to the tailings to condition them, followed by reacting the mixture with an alkaline earth metal oxide or hydroxide to raise the pH above 10Ø After a curing period, the tailings become a rock-like physically stable material.
Description
`~ 162~
This invention relates to the treatment of tailings produced during the processing of hard rock ore. Such tail-ings may for example be tailings from a flotation operation or tailings from a hydrometallurgical operation.
Hard rock ores generally consist of metal-bearing igneous and metamorphic rock which is composed of a mixture of quartz, other silicate minerals and metallic sulphides.
Metals produced through the processing of hard rock ores include gold, silver, nickel, copper, lead and zinc.
lo Processing of hard rock ores generally includes crushing the ore to a fine size and then separating the valuable metals from the remainder of the rock using a variety of methods such as flotation, flocculation, hydro-metallurgical processes, etc. The tailings from such processing have to be disposed of. The volume of the tail-ings is frequently greater than the volume of the original rock ore so that it is not possible to return all the tail-ings to the excavated area produced in mining the ore.
Other mining operations also provide other practical limita-tions on replacing the tailings underground.
The general practice of above-ground tailings disposal consists of dyking off an area and pumping the tail-ings into the area, since the tailings from most operations will be in the form of a slurry. Problems related to this disposal method include concern as to the long term stability of the dykes and a dust problem if the tailings dry out. The practice of adding cement to tailings so that they can be used as mine backfill is widespread. However, the relatively high cost of using cement to solidify tailings has generally precluded its use in treating tailings disposed of above-ground.
~ ~ 627~7 An object of the present invention is to provide an economic process which can be utilized in the treatment of tailings resulting from the processing of hard rock ores.
According to the invention, a process for the solidification of tailings produced by the processing of hard rock ore comprises conditioning the tailings with Sulphuric acid, and subsequently mixing with the conditioned tailings an additive compound comprising an alkaline earth metal oxide or hydroxide in an amount sufficlent to raise the pH of the tailings to a value in the range of from about 10 to about 14 and produce a solid product.
The amount of sulphuric acid added is preferably i`n the range of from about 0. ol % to about 5% of the dry weight of the tailings.
The alkali earth metal oxide or hydroxide may be selected from the group consisting of calcium oxide, calcium hydroxide, magnesium oxide and magnesium hydroxide. The amount of alkaline earth metal hydroxide is preferably in the range of from about 0.1% -to about 5.0% of the dry weight of the tailings.
Waste slag may be added to the tailings either prior to or after the acid addition stage, the amount of slag being in the range of from about 0.1% to about 70%
of the dry weight of the tailings.
According to a preferred embodiment, the tailings to be treated by the process of the present invention comprise a slurry of crushed rock and water, with the solids making up between about 5 and about 85% of the total weight of the slurry.
In the first stage of the process of the invention, sulphuric acid is mixed with the tailings to condition -the 1 J ~2~4~
solids for solidification. The acid added should be rela-tively concentrated in order to ultimately produce solidified material of superior strength. The amount of acid to be added is a function of the weight of the solids being treated, not of the pH of the mixture. The amount of sulphuric acid added is preferably in the range of from about 0.01 to about 5~ of the dry weight of the tailings.
After the acid addition, an alkaline earth metal oxide or hydroxide, preferably lime, is added to and mixed with the mixture to raise the pH of the mixture to a value in the range of from about 10 to about 14. Following this addition, the treated tailings may be placed in the tail-ings disposal area or in some cases used as mine backfill.In a preferred embodiment, the tailings slurry is mechani-cally thickened sufficiently such that it can be immediately deposited in such a manner as to form a hill. After a period of time, the mixture gels and sets to a single solid mass which does not break down when wet.
The sulphuric acid used in the conditioning step may be waste acid produced in the scrubbing of sulphur oxide em;ssions from smelting operations. Also, finely ground slag may be incorporated into the mixture to add to the physical strength of the waste product and to partially sub-stitute for some of the alkaline earth metal oxide or hydroxide required for the process.
Examples of the invention will now be described.
ElXAMPLE 1 Unclassified mine tailings were used in this example and were primarily composed of pyrrhotite, feldspar, quartz, mica, talc and chlorite.
~ 1~2~7 3 grams of concentrated sulphuric acid (93% H2S04) were mixed with 1250 grams of tailings (76.3% solids wt/wt).
After 15 minutes of mixing, 25 grams of calcium hydroxide were rnixed with the tailings. The mixture was then poured into sample cups and allowed to air-dry to the solid state over a period of several days. A sample of untreated tailings was also poured into a sample cup and allowed to dry.
After three days, the tailings solidified in accord- ¦
ance with the invention had an unconfirmed compressive strength in excess of 7000 psi. When samples of both the solidified and untreated tailings were immersed in water, the untreated tailings collapsed within 10 minutes while the solidified tailings had not broken down after 2 days.
Other mine tailings were found to have the following chemical composition: I
Al 7.67% ', Ca 4-33%
Fe 4-49%
K 2.32%
Na 1.29%
sio2 56.9%
10 grams of concentrated sulphuric acid were mixed with 2 kilograms of tailings (71.0% solids). After the acid and the tailings were well mixed, 80 grams of CaO were mixed with the tailings and the mixture poured into sample cups and allowed to air-dry to the solid state.
After 5 days of drying, the solidified product did not crumble when immersed in water. The unconfined compres-sive strength of a sample, as determined using a concretepenetrometer, exceeded 700 psi.
62~7 Other examples and embodiments of the invention will be apparent to a person skilled in the art, the scope of the invention being defined in the appended claims.
`: ~
This invention relates to the treatment of tailings produced during the processing of hard rock ore. Such tail-ings may for example be tailings from a flotation operation or tailings from a hydrometallurgical operation.
Hard rock ores generally consist of metal-bearing igneous and metamorphic rock which is composed of a mixture of quartz, other silicate minerals and metallic sulphides.
Metals produced through the processing of hard rock ores include gold, silver, nickel, copper, lead and zinc.
lo Processing of hard rock ores generally includes crushing the ore to a fine size and then separating the valuable metals from the remainder of the rock using a variety of methods such as flotation, flocculation, hydro-metallurgical processes, etc. The tailings from such processing have to be disposed of. The volume of the tail-ings is frequently greater than the volume of the original rock ore so that it is not possible to return all the tail-ings to the excavated area produced in mining the ore.
Other mining operations also provide other practical limita-tions on replacing the tailings underground.
The general practice of above-ground tailings disposal consists of dyking off an area and pumping the tail-ings into the area, since the tailings from most operations will be in the form of a slurry. Problems related to this disposal method include concern as to the long term stability of the dykes and a dust problem if the tailings dry out. The practice of adding cement to tailings so that they can be used as mine backfill is widespread. However, the relatively high cost of using cement to solidify tailings has generally precluded its use in treating tailings disposed of above-ground.
~ ~ 627~7 An object of the present invention is to provide an economic process which can be utilized in the treatment of tailings resulting from the processing of hard rock ores.
According to the invention, a process for the solidification of tailings produced by the processing of hard rock ore comprises conditioning the tailings with Sulphuric acid, and subsequently mixing with the conditioned tailings an additive compound comprising an alkaline earth metal oxide or hydroxide in an amount sufficlent to raise the pH of the tailings to a value in the range of from about 10 to about 14 and produce a solid product.
The amount of sulphuric acid added is preferably i`n the range of from about 0. ol % to about 5% of the dry weight of the tailings.
The alkali earth metal oxide or hydroxide may be selected from the group consisting of calcium oxide, calcium hydroxide, magnesium oxide and magnesium hydroxide. The amount of alkaline earth metal hydroxide is preferably in the range of from about 0.1% -to about 5.0% of the dry weight of the tailings.
Waste slag may be added to the tailings either prior to or after the acid addition stage, the amount of slag being in the range of from about 0.1% to about 70%
of the dry weight of the tailings.
According to a preferred embodiment, the tailings to be treated by the process of the present invention comprise a slurry of crushed rock and water, with the solids making up between about 5 and about 85% of the total weight of the slurry.
In the first stage of the process of the invention, sulphuric acid is mixed with the tailings to condition -the 1 J ~2~4~
solids for solidification. The acid added should be rela-tively concentrated in order to ultimately produce solidified material of superior strength. The amount of acid to be added is a function of the weight of the solids being treated, not of the pH of the mixture. The amount of sulphuric acid added is preferably in the range of from about 0.01 to about 5~ of the dry weight of the tailings.
After the acid addition, an alkaline earth metal oxide or hydroxide, preferably lime, is added to and mixed with the mixture to raise the pH of the mixture to a value in the range of from about 10 to about 14. Following this addition, the treated tailings may be placed in the tail-ings disposal area or in some cases used as mine backfill.In a preferred embodiment, the tailings slurry is mechani-cally thickened sufficiently such that it can be immediately deposited in such a manner as to form a hill. After a period of time, the mixture gels and sets to a single solid mass which does not break down when wet.
The sulphuric acid used in the conditioning step may be waste acid produced in the scrubbing of sulphur oxide em;ssions from smelting operations. Also, finely ground slag may be incorporated into the mixture to add to the physical strength of the waste product and to partially sub-stitute for some of the alkaline earth metal oxide or hydroxide required for the process.
Examples of the invention will now be described.
ElXAMPLE 1 Unclassified mine tailings were used in this example and were primarily composed of pyrrhotite, feldspar, quartz, mica, talc and chlorite.
~ 1~2~7 3 grams of concentrated sulphuric acid (93% H2S04) were mixed with 1250 grams of tailings (76.3% solids wt/wt).
After 15 minutes of mixing, 25 grams of calcium hydroxide were rnixed with the tailings. The mixture was then poured into sample cups and allowed to air-dry to the solid state over a period of several days. A sample of untreated tailings was also poured into a sample cup and allowed to dry.
After three days, the tailings solidified in accord- ¦
ance with the invention had an unconfirmed compressive strength in excess of 7000 psi. When samples of both the solidified and untreated tailings were immersed in water, the untreated tailings collapsed within 10 minutes while the solidified tailings had not broken down after 2 days.
Other mine tailings were found to have the following chemical composition: I
Al 7.67% ', Ca 4-33%
Fe 4-49%
K 2.32%
Na 1.29%
sio2 56.9%
10 grams of concentrated sulphuric acid were mixed with 2 kilograms of tailings (71.0% solids). After the acid and the tailings were well mixed, 80 grams of CaO were mixed with the tailings and the mixture poured into sample cups and allowed to air-dry to the solid state.
After 5 days of drying, the solidified product did not crumble when immersed in water. The unconfined compres-sive strength of a sample, as determined using a concretepenetrometer, exceeded 700 psi.
62~7 Other examples and embodiments of the invention will be apparent to a person skilled in the art, the scope of the invention being defined in the appended claims.
`: ~
Claims (5)
1. A process for the solidification of tailings produced by the processing of hard rock ore, comprising conditioning the tailings with sulphuric acid, and subsequently mixing with the conditioned tailings an additive compound comprising an alkaline earth metal oxide or hydroxide in an amount sufficient to raise the pH of the tailings to a value in the range of from about 10 to about 14 and produce a solid product.
2. A process according to claim 1 wherein the amount of sulphuric acid added is in the range of from about 0.01%
to about 5% of the dry weight of the tailings.
to about 5% of the dry weight of the tailings.
3. A process according to claim 1 wherein the alkaline earth metal oxide or hydroxide is selected from the group consisting of calcium oxide, calcium hydroxide, magnesium oxide and magnesium hydroxide.
4. A process according to claim 1 wherein the amount of alkaline earth metal oxide or hydroxide is in the range of from about 0.1% to about 5.0% of the dry weight of the tailings.
5. A process according to claim 1 wherein waste slag is added to the tailings either prior to or after the acid addition stage, the amount of slag being in the range of from about 0.1% to about 70% of the dry weight of the tailings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000354572A CA1162747A (en) | 1980-06-23 | 1980-06-23 | Process for the solidification of tailings produced by the processing of hard rock ore |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000354572A CA1162747A (en) | 1980-06-23 | 1980-06-23 | Process for the solidification of tailings produced by the processing of hard rock ore |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1162747A true CA1162747A (en) | 1984-02-28 |
Family
ID=4117239
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000354572A Expired CA1162747A (en) | 1980-06-23 | 1980-06-23 | Process for the solidification of tailings produced by the processing of hard rock ore |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1162747A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109336506A (en) * | 2018-10-31 | 2019-02-15 | 安徽固维特材料科技有限公司 | A kind of curing agent and its application method with relatively strongization ability |
-
1980
- 1980-06-23 CA CA000354572A patent/CA1162747A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109336506A (en) * | 2018-10-31 | 2019-02-15 | 安徽固维特材料科技有限公司 | A kind of curing agent and its application method with relatively strongization ability |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |