PROCESS OF EXTRACTING NICKEL SULFATE FROM ASBESTOS MINING RESIDUE

Abstract

It is provided a process for extracting nickel sulfate from mining ores, such as serpentine, comprising the steps of conducting a magnetic separation of the mining ores producing a magnetic fraction and a non magnetic fraction; leaching the non magnetic fraction with HCl producing a slurry comprising metals chloride; filtrating the slurry producing a metals chloride liquor; purifying the metals chloride liquor producing a magnesium chloride solution; separating an iron-nickel cake from the magnesium chloride solution; leaching the cake together with the magnetic fraction producing a metallic sulfate solution; extracting nickel and cobalt from the metallic sulfate solution by a ion exchange resin extraction and stripping producing an inorganic stripped phase; submitting the inorganic stripped phase to a liquid-liquid extraction producing a nickel concentrated phase; and evaporating and drying the nickel concentrated phase to recuperate nickel sulfate.

Claims

1. A process for extracting nickel sulfate from mining ores comprising the steps of: a) providing mining ores containing nickel and magnesium; b) conducting a magnetic separation of the mining ores producing a magnetic fraction and a non magnetic fraction; c) leaching the non magnetic fraction with HCl producing a slurry comprising metals chloride; d) filtrating the slurry producing a metals chloride liquor; e) purifying the metals chloride liquor producing a magnesium chloride solution; f) separating an iron-nickel cake from the magnesium chloride solution by leaching the cake together with the magnetic fraction producing a metallic sulfate solution; g) extracting nickel and cobalt from the metallic sulfate solution by a ion exchange resin extraction and stripping producing an inorganic stripped phase; h) submitting the inorganic stripped phase to a liquid-liquid extraction producing a nickel concentrated phase; and i) evaporating and drying the nickel concentrated phase to recuperate nickel sulfate.

2: The process if claim 1, further comprising a step of grinding the provided mining ores.

3: The process of any one of claim 1, wherein the mining ores are from asbestos tailing.

4: The process of claim 3, wherein the mining ores are serpentine.

5: The process of claim 1, wherein the metals chloride liquor is purified by increasing the pH.

6: The process of claim 5, wherein the pH is increased by adding magnesium oxide and an oxidizing agent.

7: The process of claim 1, wherein the metals chloride liquor is purified by precipitation at pH 5.

8: The process of claim 1, wherein the cake together and the magnetic fraction are leached with H.sub.2SO.sub.4.

9: The process of claim 1, wherein the metallic sulfate solution is further filtrated and neutralized.

10: The process of claim 9, wherein the metallic sulfate solution is neutralized with a neutralizing agent and oxidizing agent.

11: The process of claim 10, wherein the neutralizing agent is calcium oxide.

12: The process of claim 9, wherein the metallic sulfate solution pH is increased to precipitate residual metallic impurities.

13: The process of claim 12, wherein said residual metallic impurities are Fe.sub.2O.sub.3, Al, Cr, Si, Mn, Ca, or a combination thereof.

14: The process of claim 10, further comprising the step of filtrating the neutralized metallic sulfate solution separating a first portion of metal impurities.

15: The process of claim 1, wherein cobalt is extracted during the liquid-liquid extraction.

16: The process of claim 1, further comprising the step of evaporating the magnesium chloride solution providing a MgCl.sub.2 solution.

17: The process of claim 16, further comprising spray roasting the MgCl.sub.2 solution to obtain an MgO and liberate HCl gas which is recycled to the leaching step c).

18: The process of claim 16, wherein MgCl.sub.2.Math.6H.sub.2O is recovered by crystallization of the MgCl.sub.2 solution.

19: The process of claim 18, wherein the MgCl.sub.2.Math.6H.sub.2O is further dehydrated to obtain anhydrous magnesium chloride.

20: The process of claim 19, further comprising electrolysing the anhydrous magnesium chloride to recover magnesium metal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Reference will now be made to the accompanying drawings.

[0038] FIG. 1 illustrates a bloc diagram of a process according to on embodiment for producing nickel sulfate.

DETAILED DESCRIPTION

[0039] In accordance with the present disclosure there is now provided a process for asbestos tailling remediation by producing various product including nickel sulfate, amorphous silica, magnesium metal, synthetic magnesium oxide and cobalt carbonate.

[0040] As illustrated in FIG. 1, the process comprises firstly the step of leaching 10 the non magnetic fraction 9 of nickel containing ores A with dilute HCl obtaining a slurry comprising metals chloride.

[0041] In an embodiment, the non magnetic fraction 9 is the result of grinding 6 and subsequent magnetic separation 7 of nickel containing ores such as serpentine.

[0042] The slurry is filtrated 12 to obtain a metals chloride liquor and a silica by-product. The metals chloride liquor is purified 14 by increasing the pH by adding magnesium oxyde and an oxidyzing agent O producing a magnesium chloride solution. In an embodiment, the purification is accomplished by precipitation at pH 5.

[0043] Subsequently, iron, nickel residues (forming a iron nickel cake) are separated from the magnesium chloride solution.

[0044] As disclosed in table 1, the composition of the iron nickel cake shows a high presence of iron and magnesium, in addition to nickel, cobalt and silica.

TABLE-US-00001 TABLE 1 Iron-nickel-cobalt cake content Ele- Concentration Concen- Ele- Concentration Concen- ments mg/100 g tration % ments mg/100 g tration % Ag LD Na LD Al 3856 3.9 Ni 1587 1.6 As LD P 86.5 0.1 Ba 5.1 0.0 Pb 19.2 0.0 Be 0.1 0.0 Sb LD Bi LD Se LD Ca 53 0.1 Sn LD Cd LD Sr 0.2 0.0 Co 64 0.1 Ti 31.1 0.0 Cr 704 0.7 Tl LD Cu 3.8 0.0 U LD Fe 33558 33.6 V 19.2 0.0 K LD W LD Li LD Y 1.1 0.0 Mg 8702 8.7 Zn 12.5 0.0 Mn 102 0.1 B 9.6 0.0 Mo LD Si 1654 1.7 LD: limit of detection

[0045] The iron present in the cake are leached 20 together with the magnetic fraction 19 of serpentine using H.sub.2SO.sub.4.

[0046] After filtration 22 following the leaching step 20, a neutralizing agent N and an oxidizing agent O are added (e.g. calcium oxide or lime) for neutralisation 24 and the pH of the metallics sulfate solution is increased to precipitate residual metallic impurities 28 by sulfation (e.g. Fe.sub.2O.sub.3, Al, Cr, Si, Mn, Ca). Chromium sulfation follows the equation:

CrO+H.sub.2SO.sub.4=CrSO.sub.4+H.sub.2O

[0047] In an embodiment, after neturalisation 24, a filtration 25 is conducted separating a first portion of metal impurities 26 (Fe.sub.2O.sub.3, Al, Cr, Si) following a final neutralisaiton 27 to obtain maximum recovery of residual metallic impurities 28.

[0048] After neutralisation 24, nickel and cobalt are extracted by a ion exchange resin extraction step 30 using e.g. a Downex resin (e.g. DOWEX M4195 Chelating resin for copper, nickel, and cobalt). The magnesium sulfate solution remains in the leachate and is returned to the final neutralisation step 27.

[0049] After stripping of the resin M4195 loaded with Ni and Co, the elution solution loaded with Ni and Co is treated 32 by a liquid/liquid extraction with an organic solution Cyanex 272 1M at pH 6-6.5. Cobalt and other impurities are extracted 34 with the organic solution.

[0050] The residual aqueous solution then contains only Ni. The latter can, for high purity reasons, be extracted in turn, selectively by C272 1M to then produce a solution of high purity Ni sulfate.

[0051] Nickel is recuperated following evaporation 36 and cristallisation phase 38 by cooling of the nickel concentrated phase to obtain a nickel sulfate.

Nickel Recovery

[0052] After the purification and separation steps, nickel in chloride solution can also be precipitated as an hydroxide by increasing the pH with a base, such as magnesium oxide, sodium hydroxide, potassium hydroxide or a mixture thereof, until pH 6-7. The nickel precipitation step is made at 80 C. The metal is then recovered by filtration.

[0053] Alternately, the magnesium chloride solution can pass a set of ion exchange resin beds comprising a chelating resin system to catch specifically the nickel. For example, the DOWEX M4195 resin can be used for recovering nickel from acidic brine solution. In U.S. Pat. No. 5,571,308, the use of a selective resin to remove the nickel from a leach liquor is described. The absorbed element is furthermore recovered from the ion exchange resin by contacting this one with a mineral acid whish eluted the nickel.

[0054] Nickel oxide (NiO) or nickel (Ni) can be obtained by pyro-hydrolysis or electrowining of the nickel solution.

[0055] As provided herein, the nickel sulfate is extrated in a global process of valorisation of asbestos tailling. Following the purification step 14 by increasing the pH to produce the magnesium chloride solution, the magnesium brine is evaporated 40 providing a MgCl.sub.2 solution and subsequently the MgCl.sub.2 solution is spray roasted 42 to obtain an MgO and liberate HCl gas that can be returned to the HCl leaching step 10. MgCl.sub.2.Math.6H.sub.2O is recovered by crystallization 42 of a part of the brine. The recovered MgCl.sub.2.Math.6H.sub.2O is dehydrated 44 to obtain anhydrous magnesium chloride using dry gaseous hydrogen chloride. The anhydrous magnesium chloride is electrolyze 46 in an electrolytic cell fed, containing an anode and a cathode, wherein magnesium metal is recovered.

Example I

Leaching

[0056] To confirm the extraction of magnesium and nickel, magnetic fraction of serpentine tailing presented in Table 2 was leached under the conditions presented below. At the end of this step, the slurries were filtered and the leachates analyzed to know the yield of extraction of several elements. The experiments were realized in an apparatus under reflux and agitation. Magnesium extraction was beyond 90% and around 100% for nickel.

TABLE-US-00002 TABLE 2 Yield of soluble elements extraction Leaching 1 Leaching 2 Leaching 3 Conditions Conditions Conditions 300 g magnetic 150 g magnetic 200 g 1200 + 17000 1200 + 17000 magnetic proportion 50:50 proportion 50:50 1200 HCl 7M HCl 7M HCl 7M Stochiometry Stochiometry Stochiometry 1.05 1.05 1.05 90 minutes 120 minutes 120 minutes 85-90 C. 85-90 C. 80-85 C. Yield of Yield of Yield of extraction extraction extraction Elements % % % Al 57 58 54 Cr 18 24 24 Co 60 67 87 Ca 22 27 34 Fe 96 98 118 Mg 93 92 113 Mn 70 74 84 Ni 114 98 116 K 63 50 50 Ti 23 35 37 Silica residu 169 g 76 g 79 g

[0057] Table 3 shows the chemical composition on oxide base and the specific surface area of no dissolved portion from leaching 2 described in Table 1. The high SiO.sub.2 content combined with the amorphous characteristic demonstrate a great application potential in various industrial sectors.

TABLE-US-00003 TABLE 3 Chemical composition of silica fraction from leaching 2 SiO2 Al2O3 Fe2O3 MgO CaO Na2O K2O TiO2 P2O5 Mn3O4 Cr2O3 NiO LOI Sum 88.3% 1.1% 2.0% 4.6% 1.0% 0.1% 0.1% 0.1% 0.0% 0.1% 1.1% 0.0% 1.0% 99.5% BET: 390 000 m.sup.2/g

[0058] While the present disclosure has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations including such departures from the present disclosure as come within known or customary practice within the art to and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.