FI20180022A1 - Chemical method ion - Google Patents

Abstract

The invention is directed to purification method comprising removal of harmful ion species from a complex water solution that comprises mainly salt ions of sulfate, calsium, sodium and magnesium, and more than 0.1 gram/liter of aluminium and manganese, wherein the complex water solution is further treated chemically to precipitate and remove major contaminating substances including precipitation of magnesium as magnesium hydroxide, or as a carbonate, and wherein the complex water solution is derived from waste water of certain (bio)heap leaching maining process of nickel, cobolt, zinc and copper.

Description

BACKGROUND OF THE INVENTION

Various chemical methods are also known for removal of harmful substances. The present invention is directed to a chemical process for removal of harmful salts from a complex water solution.

The invention is directed to the removal of contaminant salt ions calcium and magnesium from complex water according to the invention. The invention is further directed to removal of novel contaminants.

The removal of magnesium and calcium is known from various mining water contexts. However, these are less well known from waters derived from (bio)heap leaching of sulfidic nickel-zinccopper-cobalt ores, and especially black schist ore with sulfidic nickel, zinc, copper, and cobalt as a major product metals. It is realized, that Sumitomo metal mining co EP application no 13 803 603.3 described alkaline treatment of waters from a different major type of ore, which is oxide ore called laterite and which is pressure leached. There is magnesium mentioned as an impurity metal (with iron and manganese). The second and final neutralization is performed with a range of pH 8.5 and 9.5. This is quite in contrast to the magnesium removal of present invention at about pH 11.

The present invention is further direct to removal of magnesium or magnesium and calcium at an elevated temperature and both substantially as carbonates.

The present invention reveals integrated methods to remove divalent cations.

SUMMARY OF THE INVENTION

The invention is directed to the removal of contaminant salt ions such as calcium and magnesium from complex water according to the invention. The invention includes methods for removing harmful cations by precipitation.

The present invention is in an embodiment directed to a method for purification of a complex mixture of elements in a water solution, referred as a complex water, wherein Ca²⁺ ion is precipitated from the solution as calcium carbonate CaCCh. The method for purifying complex water comprises a step of precipitating Ca²⁺ by adding a carbonate source such as CO2 gas or carbonate containing liquid to precipitate CaCCh, this also referred as precipitation of calcium. In an embodiment the solid CaCCh fraction is recovered and used in the process as a base or further processed to CaO or Ca(OH)2, preferably processed to Ca(OH)2 and used in the process of producing the complex water for alkaline precipitation. It is realized that Ca(OH)2 of surprisingly high quality can be produced.

The invention revealed that the precipitation of CaCCh improves the quality of the complex water and will allow its better use for further processing such as use in a bioreactor producing carbonate and/or prior to reverse osmosis. A preferred bioreactor is an anaerobic bioreactor producing H2S.

In an embodiment the complex water has been produced in a mining process, wherein a pregnant leach solutions (PLS) is produced by (bio)heap leaching, commercial metals have been recovered by sulfide precipitation, iron containing fraction has been precipitated by alkaline and final neutralization has been performed by alkaline to about pH 8-10 precipitating a gypsum containing fraction. The mainly salt containing complex water is optionally concentrated by reverse osmosis to produce a preferred complex water with higher salt concentrations. The reverse osmosis produces also a more purified water fraction, with sulfate concentration below 200 mg/L. In an embodiment the step of precipitating the Ca²⁺ ion is performed before the reverse osmosis step in order to reduce the scaling of the reverse osmosis membranes. In an embodiment this method further comprises an optional step of precipitating the Ca²⁺ ion after reverse osmosis.

The present invention is in an embodiment directed to a method for purification of a complex mixture of elements in a water solution, referred as a complex water, wherein Mg²¹ ion is precipitated from the solution, in some embodiments as magnesium hydroxide Mg(OH)2 or as a carbonate, including MgCCh optionally in a form comprising hydrate and/or hydroxyl structures. In an embodiment MgCCh is precipitated, optionally with CaCCh, at an elevated temperature.

The present invention is directed to a method wherein the Mg²¹ ion is precipitated from the solution after current step of the final neutralization of the process water in a black shale ore or an Eastern Finland black shale ore using process. In an embodiment this is done by adding an alkaline substance such NaOH or Ca(OH)2, preferably Ca(OH)2, as to precipitate Mg(OH)2 at about pH 11, and optionally Mg(OH)2 is recovered as a useful product. The magnesium hydroxide precipitation is performed at normal process or outdoor temperatures such as between 0 and 35 degrees of Celsius. Present invention realized a process, wherein the final neutralization is performed at pH of about 810.0 or 8.5-9.5 and magnesium fraction is precipitated after that at about pH 11.0.

The preferred process according to the invention comprises steps

1. optionally treating complex water by precipitating magnesium hydroxide and calcium carbonate; or calcium carbonate, and optionally recovering magnesium hydroxide and/or calcium carbonate

2. optionally directing the water produced to reverse osmosis

3. treating complex water by precipitating calcium carbonate

4. directing the water to process water circulation for (bio)heap leaching, to waste water or to bioreactor to produce sulfides or to reverse osmosis.

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The claims of the invention include following

1. A purification method comprising removal of harmful ion species in a complex water comprising following major salt ions: more than 1 gram/liter of sulfate and calcium, and sodium and/or magnesium, and more than 0.1 gram/liter of aluminum and optionally also manganese, wherein the complex water is further chemically to precipitate and remove major contaminating substances including precipitation of magnesium as magnesium hydroxide, Mg(OH)2, or as a carbonate and/or calcium as calcium carbonate, CaCOs.

2. A purification method comprising removal of harmful ion species in a complex water produced through steps of

i) (bio)heap leaching of a sulfidic multi-metal ore and solubilization of metals in sulfuric acid containing process solution, when leaching is performed in heaps under normal outdoor pressure and temperature,

20180022 prh 19 -02- 2018 ii) a hydrogen sulfide precipitation of all or several product metal-elements selected from the group copper, zinc, nickel and cobalt.

iii) optional use of magnesium substance such as MgO or Mg(OH)2 to adjust pH, optionally to remove residual hydrogen sulfide gas, iv) optional extraction of uranium by uranium binding substance, and/or alkaline earth metals by alkaline earth metal binding substance and organic solvent,

v) alkaline neutralization step comprising precipitation of a major iron comprising fraction, and vi) final neutralization at about pH 8-9.5 by calcium hydroxide to produce gypsum-metal precipitate, wherein the complex water is further treated chemically to precipitate and remove major contaminating substances including precipitation of magnesium as magnesium hydroxide, Mg(OH)2, or as a carbonate and/or calcium as calcium carbonate, CaCCh.

3. The method of purifying of claim 1, wherein the complex water is produced as described in claim 2.

4. The method of any of the claims 1-3, comprising a step of precipitating Ca²⁺ by adding a carbonate source such as CO2 gas or carbonate containing liquid to precipitate CaCCh.

5. The method of any of the claims 1-4, comprising a step of adjusting pH close 11 by a hydroxide base and precipitating Mg²' as Mg(OH)2, optionally this magnesium precipitation step is performed before precipitation of calcium.

6. The method of any of the claims 1-4, comprising a step of adding a carbonate source precipitating Mg²* as a MgCCh, optionally at an elevated temperature, and optionally this magnesium precipitation step is performed before precipitation of calcium.

7. The method of claim 6, wherein the method is performed at an elevated temperature, and magnesium precipitation step is performed before or simultaneously with the precipitation of calcium.

8. The method of any of the claims 2-7, wherein the process further comprises a step iii) as described in claim 2 of adding magnesium alkaline substance, optionally Mg(OH)2.

9. The method of any of the claims 2-8, wherein the method comprises precipitation of both magnesium and calcium.

10. The method of any of the claims 2-9, wherein the ore used in the step i) is a black shale ore.

11. The method of any of the claims 2-10, wherein the metal-elements produced include copper, zinc, nickel and cobalt.

12. The method of any of the claims 2-11, wherein the metal-elements produced include copper, zinc, nickel and cobalt.

13. The method of any of the claims 1-12, wherein CaCCh and/or Mg(OH)2 and/or a magnesium carbonate are recovered for to be used in the process, or as product or waste fractions, preferably Mg(OH)2 is directed to a product or a waste fraction.

14. The method of any of claims 1-13, wherein the water produced is treated in a bioreactor to produce sulfides.

15. The method of any of the claims 1-14, wherein the complex water is derived (bio)heap leaching of a nickel ore, optionally a black schist ore, after treatment of the PLS solution by sulfides to precipitate product metals and after final neutralization of the water, and further after concentrating the water by reverse osmosis.

16. The method according to any of claims 1-15, wherein the complex water comprises sulfate concentration selected from a group between 0.5 to 50 grams/liter, 2.0 g/L to 30 g/L, 3.0 g/L to 20.0 g/L, or 4.0 to 15 g/L, and optionally calcium concentrations are between 0.5 to 25 grams/liter, 0.5 g/L to 15 g/L, 1.0 g/L to 10.0 g/L, 2.0 to 8 g/L, and magnesium concentrations are between 0.5 to 25 grams/liter, 1.0 g/L to 22 g/L, 4.0 g/L to 20.0 g/L, 6.0 to 18 g/L, or 8.0 to 18 g/L, and optionally sodium concentrations are between 0.5 to 25 grams/liter, 0.5 g/L to 15 g/L, 1.0 g/L to 10.0 g/L, 2.0 to 8 g/L.

17. The method according to any of claims 1-16, wherein the complex water comprises sulfate concentration selected from a group between 0.5 to 50 grams/liter, 2.0 g/L to 30 g/L, 3.0 g/L to 20.0 g/L, or 4.0 to 15 g/L, and optionally sodium concentration (weight/volume) is about 20%-80%, 25%-75%, 30%- 70%, 35-65 %, 40-60% of the concentration of sulfate.

18. A method according to any of claims 1-17, wherein the complex water comprises sulfate concentration selected from a group between 0.5 to 50 grams/liter, 2.0 g/L to 30 g/L, 3.0 g/L to 20.0 g/L, or 4.0 to 15 g/L, and optionally calcium concentration (weight/volume) is about 20%-80%, 25%-75%, 30%- 70%, 35-65 %, 40-60% of the concentration of sulfate.

19. A method according to any of claims 1-18, wherein the complex water is derived from waste waters of (bio)heap leaching mining process comprises metal precipitation supernatant liquid derived from metal factory of (bio)heap leaching process of low metal content sulfidic ore comprising: nickel, copper, zinc and cobalt as major product metals, and further comprising iron, manganese, aluminum, chromium as potential contamination substances, and optionally the ore is the ore is an Eastern Finland black shale, and further optionally the metal precipitation is the optimized metal precipitation process for a mine using an Eastern Finland black shale ore.

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DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to methods for purification of magnesium and/or calcium ions from the complex water.

In an embodiment the invention is directed to method for treatment of water derived from following process:

A purification method comprising removal of harmful ion species in a complex water produced through steps of

i) (bio)heap leaching of a sulfidic multimetal ore and solubilization of metals in sulfuric acid containing process solution, when leaching is performed in heaps under normal outdoor pressure and temperature, ii) a hydrogen sulfide precipitation of all or several product metal-elements selected from the group copper, zinc, nickel and cobalt.

20180022 prh 19 -02- 2018 iii) optional use of magnesium substance such as MgO or Mg(OH)2 to adjust pH, optionally in a gas washing step to remove residual hydrogen sulfide gas, iv) optional extraction of uranium by uranium binding substance, and/or alkaline earth metals by alkaline earth metal binding substance and organic solvent,

v) alkaline neutralization step comprising precipitation of a major iron comprising fraction, and vi) final neutralization at about pH 8-9.5 by calcium hydroxide to produce gypsum-metal precipitate, wherein the complex water is further treated to remove substantial part of a major contaminating substance selected from the group magnesium, calcium or sulfate. In an embodiment the compelx water is treated chemically to precipitate and remove major contaminating substances including precipitation of magnesium as magnesium hydroxide, Mg(OH)2 or MgCOs, and/or calcium as calcium carbonate, and/or treated biologically to remove of sulfate by a bioreactor producing hydrogen sulfide and/or in an embodiment producing a biosolution of sulfides and carbonates. In an embodiment the process comprises precipitation of magnesium, and a step iii) of adding magnesium alkaline substance such as Mg(OH)2. In an embodiment the process comprises precipitation of calcium and magnesium, and in another embodiment the process comprises at least precipitation of calcium and biologic removal of sulfate. In an embodiment the process comprises precipitation of both magnesium and calcium and biologic removal of sulfate.

In an embodiment regarding to the step i) said sulfidic multi-metal ore is a black shale ore (also referred as a black schist ore), and in other embodiments the black shale ore is an Eastern Finland black shale ore or substantially similar ore or equivalent ore. In an embodiments of the step i) solubilizing metal in sulfuric acid containing process water solution is performed with pumping air to the heaps through pipes. In some embodiments of the step i) the heaps are operated under normal outdoor pressure and temperature of Eastern Finland, or of middle Eastern Finland or of the black shale region of Eastern Finland according to the invention, or under substantially similar pressure and temperature conditions or under equivalent pressure and temperature conditions. In an embodiment regarding to the step ii) a hydrogen sulfide precipitation of the product metalelements of the group copper, zinc, nickel and cobalt is performed, and in another embodiment hydrogen sulfide precipitation of the product metal-elements of the group copper, zinc, nickel and cobalt is performed.

The present invention is in an embodiment directed to a method for purification of a complex mixture of elements in a water solution, referred as a complex water, wherein Ca²⁺ ion is precipitated from the solution as calcium carbonate CaCOs. The method for purifying complex water comprises a step of precipitating Ca²⁺ by adding a carbonate source such as CO2 gas or carbonate containing liquid to precipitate CaCOs, this also referred as precipitation of calcium. In an embodiment carbodioxide is used to generate carbonates in the water.

In an embodiment the solid CaCOs fraction is recovered and used in the process as a base or further processed to CaO or Ca(OH)2, preferably processed to Ca(OH)2 and used in the process of producing the complex water for alkaline precipitation. It is realized that Ca(OH)2 of surprisingly high quality can be produced. In some embodiments the purity of Ca(OH)2 is at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95%. The recovered Ca(OH)2 is useful as it is practically devoid of harmful impurities such as heavy metals, iron and aluminum. In an embodiment the content of harmful impurities is less than 35 %, less than 25 %, less than 15 %, or less than 10 %.

The invention revealed that the precipitation of CaCOs improves the quality of the complex water and will allow its better use for further processing such as use in a bioreactor producing carbonate and/or prior to reverse osmosis, or recycling the water for (bio)heap leaching process.

20180022 prh 19 -02- 2018

In an embodiment the complex water has been produced in a mining process, wherein a pregnant leach solutions (PLS) is produced by (bio)heap leaching, commercial metals have been recovered by sulfide precipitation, iron containing fraction has been precipitated by alkaline and final neutralization has been performed by alkaline to about pH 8-10 precipitating a gypsum containing fraction. The mainly salt containing complex water is optionally concentrated by reverse osmosis to produce a preferred complex water with higher salt concentrations. The reverse osmosis produces also a more purified water fraction, with sulfate concentration below 200 mg/L. In an embodiment the step of precipitating the Ca²⁺ ion is performed before the reverse osmosis step in order to reduce the scaling of the reverse osmosis membranes. In an embodiment this method further comprises an optional step of precipitating the Ca²⁺ ion after reverse osmosis.

The present invention is in an embodiment directed to a method for purification of a complex mixture of elements in a water solution, referred as a complex water, wherein Mg²' ion is precipitated from the solution, in some embodiments as magnesium hydroxide Mg(OH)₂ or as MgCCh. In an embodiment MgCCh is precipitated, optionally with CaCCh, at an elevated temperature.

In another embodiment the method for purifying complex water comprises a step of precipitating Mg² * by adding an alkaline substance such NaOH or Ca(OH)₂ or carbonate source, in an embodiment Ca(OH)₂, as to precipitate Mg(OH)₂ at about pH 11. The preferred pH range is between 10.5 and 11.5. In an embodiment the solid Mg(OH)₂ fraction is recovered and used in the process as a base, or provided or sold for use as a magnesium reagent. In an embodiment the invention is directed to the precipitation of magnesium, when the process includes use of a magnesium alkaline substance for adjusting pH of the solution. It is realized that removal and/or recycling of magnesium is especially useful in such process.

In an embodiment, the invention is directed to at least partial removal of magnesium from the process, to a commercial product or to a waste fraction. It is realized that Mg(OH)₂ of surprisingly high quality can be produced. In some embodiments the purity of Mg(OH)₂ is at least 30%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or at least 95%. The recovered Mg(OH)₂ is useful as it is practically devoid of harmful impurities such as heavy metals, iron and aluminum. In an embodiment the content of harmful impurities is less than 35 %, less than 25 %, less than 15 %, or less than 10 %. The impurities in magnesium hydroxide fraction includes calcium sulfate (gypsum).

In an embodiment magnesium carbonate is precipitated in a hydrate form or hydroxy-hydrate form, magnesite (MgCCh), lansfordite (MgCO3-5H2O), nesquehonite (MgCO3-3H2O), and barringtonite (MgCO3-2H2O), and hydroxy-hydrates: hydromagnesite [Mgs(CO3)4(OH)₂.4H₂O], artinite [MgCO3-Mg(OH)2-3H2O], dypingite [4Mg(CO3)Mg(OH)2 5H2O]. A preferred hydrate form is nesquehonite MgCCh 3H₂O.

The present invention is directed to a method wherein the Mg²⁺ ion is precipitated from the solution after current step of the final neutralization of the process water in black shale ore or Eastern Finland black shale ore using process. In an embodiment this is done by adding an alkaline substance such NaOH or Ca(OH)₂, preferably Ca(OH)₂, as to precipitate Mg(OH)₂ at about pH 11, and optionally Mg(OH)2 is recovered as a useful product. The magnesium hydroxide precipitation is performed at normal process or outdoor temperatures such as between 0 and 35 degrees of Celsius. In another embodiment magnesium is precipitated as a carbonate according to the invention and optionally at on elevated temperature according to the invention.

Present invention realized a process, wherein the final neutralization is performed at pH of about 8

20180022 prh 19 -02- 2018

10.0 or 8.5-9.5 and magnesium fraction is precipitated after that at about pH 11.0.

In another embodiment the final neutralization step is performed to pH 11.0 and the magnesium hydroxide is included in the waste fraction produced by the final neutralization. However, present inventors realized a major problem with such process. The current final neutralization fraction of Eastern Finland black shale mine type waters would contain metal precipitating most effectively with acidic pH like aluminum (Al). When pH would be increased to precipitate magnesium, metals like aluminum would get more soluble. Therefore present invention realized a process, wherein the final neutralization is performed at pH of about 8-10.0 or 8.5-9.5 and magnesium fraction is precipitated after that at about pH 11.0. Additionally the process of an Eastern Finland black shale mine water contain substantial amount of sodium and/or magnesium derived from neutralization and/or residual hydrogen sulfide gas removal steps.

After the precipitation of Mg²* ion, Ca²⁺ ion is precipitated as carbonate according to the invention, and optionally Ca(OH)2 is recovered as a useful product. This will lower the pH of the complex water reaction. In an embodiment the final pH is between 8.5-9.5, 8.5-9.3 or between 8.6-8.9. In an embodiment the complex water is then concentrated by reverse osmosis and/or treated in a bioreactor. In an embodiment the complex water is treated first by reverse osmosis, the optionally more calcium precipitated as carbonate according invention, and optionally calcium carbonate is recovered, and the complex water is directed to the bioreactor for producing sulfides and reducing the amount of sulfate.

In an embodiment the carbonate step is performed only partially or it is performed by exposing the water to natural carbon dioxide in an open water reservoir for a longer time. The present invention is directed to the natural carbon dioxide method and preferably to a method of measuring CaCCE precipitating into the reservoir and/or carbonate level and/or pH of the water and potential recovery of the fraction by dredging and/or sucking the sludge from the bottom of the reservoir.

Precipitation at an elevated temperature

In an embodiment MgCCE and/or CaCCE are precipitated by a carbonate source at an elevated temperature. In an embodiment both MgCO ? and CaCCE are precipitated at an elevated temperature. In an embodiment MgCCE is precipitated, optionally with CaCCE. at an elevated temperature. In an embodiment mostly CaCCE is precipitated at an elevated temperature. The elevated temperature is below boiling point of the complex water and in some embodiments above of about 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees, 70 degrees, 75 degrees, 78 degrees, 80 degrees, or 82 degrees of Celsius. In some embodiment the elevated temperature is about 73 degrees, 76 degrees, 78 degrees, 80 degrees, 82 degrees or 84 degrees of Celsius, and about meaning in some embodiments +-10 degree, or +-5 degrees or +-3 degrees.

In some embodiments temperature is in a lower temperature range above of about 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, about meaning in some embodiments +10 degree, or +-5 degrees or +-3 degrees. In an embodiment magnesium carbonate is precipitated as a hydrate form when the temperature is in the lower range. The preferred hydrate form is nesquehonite MgCCEGIhO. In an embodiment the complex water is treated with calcium hydroxide to reach pH between 9.0-10.5, or 9.5-10.5 or 10-10.5 and the temperature of the water is elevated to level between 35-55, or between 38 -52, or between 38-45 degrees of Celsius. It is realized that alkaline precipitation may rise the temperature to the preferred level or even higher. Then carbonate source is added and magnesium is precipitated as a hydroxy-carbonate, in an embodiment as nesquehonite MgCCE 3H2O, and optionally also calcium carbonate is precipitated as CaCCE. In an embodiment carbon dioxide CO2 is used for carbonate source, and pH is lowered to about 8.6 or to about 8.8, and both CaCCE and MgCCE hydrate, in an embodiment MgCCE 3H2O, are precipitated. In an embodiment a substance reducing the hydration of MgCCE is used, in an embodiment the substance is an organic substance, such as a carbon source of the bioreactor.

In an embodiment a substance increasing the precipitation of CaCCh is used, in an embodiment the substance is a form of CaCCh.

20180022 prh 19 -02- 2018

The preferred process according to the invention comprises steps

1. optionally treating complex water by precipitating magnesium hydroxide or carbonate and calcium carbonate; or calcium carbonate, and optionally recovering magnesium hydroxide/carbonate and/or calcium carbonate

2. optionally directing the water produced to reverse osmosis

3. treating complex water by precipitating calcium carbonate

4. directing the water to process water circulation for (bio)heap leaching, to waste water or to bioreactor to produce sulfides or to reverse osmosis.

The preferred process according to the invention comprises steps optional process steps 1 and 2:

1. Precipitation of magnesium from process water as magnesium hydroxide and/or carbonate, and

1.1. optional recovery of magnesium hydroxide/carbonate as a product, and

1.2 precipitation of calcium as calcium carbonate, and

1.3. optional recovery of calcium carbonate as a product or

1.5. Precipitation of calcium from process water as calcium carbonate, and

1.6. optional recovery of calcium carbonate as a product and

2. Treatment of water recovered from step 1.2. or 1.5. by reverse osmosis to obtain concentrated complex water

3. Precipitation of calcium from complex water as calcium carbonate, and

3.1. optional recovering of calcium carbonate as a product

4. directing the water to process water circulation for (bio)heap leaching, to waste water or to bioreactor to produce sulfides or to reverse osmosis.

Complex water

Present invention is directed to methods for purification water and recycling of sulfate from an industrial sulfate and metal comprising water solution referred as a complex water. It is realized that handling of a complex water is challenging task. In an embodiment the complex water comprises i) high level of sulfate, ii) high level of at least one earth alkaline metal cation such as Ca²⁺ and/or Mg^2<, iii) high level of alkaline metal cation selected from group K⁺ and/or Na⁺, and optionally further comprises major impurities selected from the group iron, aluminum and manganese, and optionally further comprises at least one heavy metal impurity selected from the group nickel, zinc, cobalt, copper, and chromium, in an embodiment as a form of cation Ni²⁺, Zn²⁺, Co²⁺, Cu²⁺, Cr²* and Cd²⁺, optionally further comprising a radioactive impurity selected from a group an isotope of uranium, radium, and thorium.

The invention is directed to a purification method comprising removal of harmful ion species in a complex water comprising following major salt ions: more than 1 gram/liter of sulfate and calcium, and sodium and/or magnesium, and more than 0.1 gram/liter of aluminum and optionally also more than 0.1 gram/liter manganese.

In some embodiments the high level elements are present at concentrations between 0.1 to 50 grams/liter, 0.5 g/L to 30 g/L, 2.0 g/L to 20.0 g/L, 2.5 to 15 g/L. In some embodiments sulfate concentrations are between 0.5 to 50 grams/liter, 2.0 g/L to 30 g/L, 3.0 g/L to 20.0 g/L, 4.0 to 15 g/L. In some embodiments calcium concentrations are between 0.5 to 25 grams/liter, 0.5 g/L to 15 g/L, 1.0 g/L to 10.0 g/L, 2.0 to 8 g/L. In an embodiment magnesium concentrations are between 0.5 to 25 grams/liter, 1.0 g/L to 22 g/L, 4.0 g/L to 20.0 g/L, 6.0 to 18 g/L, or 8.0 to 18 g/L. In some embodiments sodium concentrations are between 0.5 to 25 grams/liter, 0.5 g/L to 15 g/L, 1.0 g/L to 10.0 g/L, 2.0 to 8 g/L. In an embodiment sodium and calcium concentrations (weight/volume) are about 20%-80%, 25%-75%, 30%- 70%, 35-65 %, 40-60% of the concentration of sulfate.

In an embodiment the complex water comprises sulfate concentration selected from a group between 0.5 to 50 grams/liter, 2.0 g/L to 30 g/L, 3.0 g/L to 20.0 g/L, or 4.0 to 15 g/L, and optionally sodium concentration (weight/volume) is about 20%-80%, 25%-75%, 30%- 70%, 35-65 %, 40-60% of the concentration of sulfate.

In an embodiment the complex water comprises sulfate concentration selected from a group between 0.5 to 50 grams/liter, 2.0 g/L to 30 g/L, 3.0 g/L to 20.0 g/L, or 4.0 to 15 g/L, and optionally calcium concentration (weight/volume) is about 20%-80%, 25%-75%, 30%- 70%, 3565 %, 40-60% of the concentration of sulfate.

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The complex water is e.g. waste or processed water derived from a mining or a forestry process. The invention is directed to a process according to the invention, wherein the complex water is derived from waste/process liquids derived from a process selected from the group: metal precipitation and/or (bio)heap leaching mining process, and or/acid mine drainage from a sulfide ore and/or processed element comprising derivatives of any of the previous ones.

Preferred ore and process type producing complex water

The invention includes any process of invention, wherein the complex water is derived from waste waters of (bio)heap leaching mining process comprises metal precipitation supernatant liquid derived from metal factory of (bio)heap leaching process of sulfide black schist/shale ore.

The preferred black shale ore is a Eastern Finland type ore or similar to it. In an embodiment the Eastern Finland black shale comprises carbon and sulfur content between about 4-10 % and the average nickel content is between 0.1-0.4 %, zinc content between 0.3-0.75%, and copper 0.050.25 %.

The Eastern Finland black shale ores have been further defined by Kirsti Loukola-Ruskeeniemi https://www.researchgate.net/profile/Kiisti_Loukola-

Ruskeeniemi/publication/264315212_Geochemistry of Proterozoic metamorphosed black shale sineastemFinlandwithimplicationsforexplorationandenvironmentstudies/links/53d8c47 30cf2e38c6331a0b8/Geochemistry-of-Proterozoic-metamorphosed-black-shales-in-eastemFinland-with-implications-for-exploration-and-environment-studies.pdf

The invention is directed to processes, wherein the complex water is derived from waste waters of (bio)heap leaching mining process comprises metal precipitation supernatant liquid derived from metal factory of (bio)heap leaching process of low metal content sulfidic ore comprising: nickel, copper, zinc and cobalt as major potential product metals, and further comprising iron, manganese, aluminum, and chromium as potential contamination substances, and optionally the ore is the an Eastern Finland black shale ore according to the invention, and further optionally the metal/element precipitation is directed to optimization of the current metal precipitation process of the preferred metal production process.

The Eastern Finland black shale mine process

An embodiment of the invention includes processes, wherein the complex water is derived from waste waters of (bio)heap leaching mining process comprises metal precipitation supernatant liquid derived from metal factory of (bio)heap leaching process of low metal content sulfidic ore comprising at least one and in an embodiment all metals selected from the group: nickel, copper, zinc and cobalt as major product metals.

EXAMPLES

Example 1. Water similar to an Eastern Finland black shale mine waste water or waste water treated by reverse osmosis comprising salts and impurities is treated by an hydroxide base adjusting pH to about 11 and precipitating Mg²¹ as Mg(OH)2 or by a carbonate source at an elevated temperature to precipitate aMgCCL. The treated water is mixed with carbonates from CO2 gas or carbonate containing liquid to precipitate CaCCh.

Example 2. Water similar to an Eastern Finland black shale mine waste water or waste water treated by reverse osmosis comprising salts and impurities is treated by carbonates from CO2 gas or carbonate containing liquid to precipitate CaCCL.

Example 3. Water similar to an Eastern Finland black shale mine waste water or waste water treated by reverse osmosis comprising salts and impurities is treated in an anaerobic bioreactor and and sulfides and bicarbonate is formed. It is realized that calcium carbonate is formed in the bioreactor affecting the process and when accumulating clogging the reactor and/or it pipelines. When water from example 1 or 2 is used, the amount of CaCCh is reduced in bioreactor, in reverse osmosis or in other parts of the process including the (bio)heap leaching.

Claims (19)

1. A purification method comprising removal of harmful ion species in a complex water comprising following major salt ions: more than 1 gram/liter of sulfate and calcium, and sodium and/or magnesium, and more than 0.1 gram/liter of aluminum and optionally also manganese, wherein the complex water is further chemically to precipitate and remove major contaminating substances including precipitation of magnesium as magnesium hydroxide, Mg(OH)2, or as a carbonate and/or calcium as calcium carbonate, CaCOs.

2. A purification method comprising removal of harmful ion species in a complex water produced through steps of

i) (bio)heap leaching of a sulfidic multi-metal ore and solubilization of metals in sulfuric acid containing process solution, when leaching is performed in heaps under normal outdoor pressure and temperature, ii) a hydrogen sulfide precipitation of all or several product metal-elements selected from the group

20180022 prh 19 -02- 2018 copper, zinc, nickel and cobalt, iii) optional use of magnesium substance such as MgO or Mg(OH)2 to adjust pH, optionally to remove residual hydrogen sulfide gas, iv) optional extraction of uranium by uranium binding substance, and/or alkaline earth metals by alkaline earth metal binding substance and organic solvent,

v) alkaline neutralization step comprising precipitation of a major iron comprising fraction, and vi) final neutralization at about pH 8-9.5 by calcium hydroxide to produce gypsum-metal precipitate, wherein the complex water is further treated chemically to precipitate and remove major contaminating substances including precipitation of magnesium as magnesium hydroxide, Mg(OH)2, or as a carbonate and/or calcium as calcium carbonate, CaCCh.

3. The method of purifying of claim 1, wherein the complex water is produced as described in claim 2.

4. The method of any of the claims 1-3, comprising a step of precipitating Ca²⁺ by adding a carbonate source such as CO2 gas or carbonate containing liquid to precipitate CaCCh.

5. The method of any of the claims 1-4, comprising a step of adjusting pH close 11 by a hydroxide base and precipitating Mg²* as Mg(OH)2, optionally this magnesium precipitation step is performed before precipitation of calcium.

6. The method of any of the claims 1 -4, comprising a step of adding a carbonate source precipitating Mg²* as a MgCCh, optionally at an elevated temperature, and optionally this magnesium precipitation step is performed before precipitation of calcium.

7. The method of claim 6, wherein the method is performed at an elevated temperature, and magnesium precipitation step is performed before or simultaneously with the precipitation of calcium.

8. The method of any of the claims 2-7, wherein the process further comprises a step iii) as described in claim 2 of adding magnesium alkaline substance, optionally Mg(OH)2.

9. The method of any of the claims 2-8, wherein the method comprises precipitation of both magnesium and calcium.

10. The method of any of the claims 2-9, wherein the ore used in the step i) is a black shale ore.

11. The method of any of the claims 2-10, wherein the metal-elements produced include copper, zinc, nickel and cobalt.

12. The method of any of the claims 2-11, wherein the metal-elements produced include copper, zinc, nickel, and cobalt..

13. The method of any of the claims 1-12, wherein CaCCh and/or Mg(OH)2 and/or a magnesium carbonate are recovered for to be used in the process, or as product or waste fractions, preferably Mg(OH)2 is directed to a product or a waste fraction.

14. The method of any of claims 1-13, wherein the water produced is treated in a bioreactor to produce sulfides.

15. The method of any of the claims 1-14, wherein the complex water is derived (bio)heap leaching of a nickel ore, optionally a black schist ore, after treatment of the PLS solution by sulfides to precipitate product metals and after final neutralization of the water, and further after concentrating the water by reverse osmosis.

16. The method according to any of claims 1-15, wherein the complex water comprises sulfate concentration selected from a group between 0.5 to 50 grams/liter, 2.0 g/L to 30 g/L, 3.0 g/L to

20.0 g/L, or 4.0 to 15 g/L, and optionally calcium concentrations are between 0.5 to 25 grams/liter, 0.5 g/L to 15 g/L, 1.0 g/L to 10.0 g/L, 2.0 to 8 g/L, and magnesium concentrations are between 0.5 to 25 grams/liter, 1.0 g/L to 22 g/L, 4.0 g/L to 20.0 g/L, 6.0 to 18 g/L, or 8.0 to 18 g/L, and optionally sodium concentrations are between 0.5 to 25 grams/liter, 0.5 g/L to 15 g/L, 1.0 g/L to 10.0 g/L, 2.0 to 8 g/L.

17. The method according to any of claims 1-16, wherein the complex water comprises sulfate concentration selected from a group between 0.5 to 50 grams/liter, 2.0 g/L to 30 g/L, 3.0 g/L to 20.0 g/L, or 4.0 to 15 g/L, and optionally sodium concentration (weight/volume) is about 20%80%, 25%-75%, 30%- 70%, 35-65 %, 40-60% of the concentration of sulfate.

18. A method according to any of claims 1-17, wherein the complex water comprises sulfate concentration selected from a group between 0.5 to 50 grams/liter, 2.0 g/L to 30 g/L, 3.0 g/L to 20.0 g/L, or 4.0 to 15 g/L, and optionally calcium concentration (weight/volume) is about 20%80%, 25%-75%, 30%- 70%, 35-65 %, 40-60% of the concentration of sulfate.

19. A method according to any of claims 1-18, wherein the complex water is derived from waste waters of (bio)heap leaching mining process comprises metal precipitation supernatant liquid derived from metal factory of (bio)heap leaching process of low metal content sulfidic ore comprising: nickel, copper, zinc and cobalt as major product metals, and further comprising iron, manganese, aluminum, chromium as potential contamination substances, and optionally the ore is the ore is an Eastern Finland black shale, and further optionally the metal precipitation is the optimized metal precipitation process for a mine using an Eastern Finland black shale ore.