AU2007231801A1

AU2007231801A1 - Leaching of oxidised molybdenum

Info

Publication number: AU2007231801A1
Application number: AU2007231801A
Authority: AU
Inventors: Frank Trask; William Stanley Yeaman
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-11-02
Filing date: 2007-11-01
Publication date: 2008-05-22

Description

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AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT (Original) APPLICATION NO:

LODGED:

COMPLETE SPECIFICATION LODGED:

ACCEPTED:

PUBLISHED:

RELATED ART: NAME OF APPLICANTS: ACTUAL INVENTORS: ADDRESS FOR SERVICE: INVENTION TITLE: Frank Trask William Stanley Yeaman Frank Trask William Stanley Yeaman LORD AND COMPANY, Patent and Trade Mark Attorneys, of 4 Douro Place, West Perth, Western Australia, 6005, AUSTRALIA.

LEACHING OF OXIDISED MOLYBDENUM DETAILS OF ASSOCIATED AUSTRALIAN PROVISIONAL APPLICATION NO'S: 2006906110 filed November 2, 2006; and 2007901388 filed March 16, 2007 The following Statement is a full description of this invention including the best method of performing it known to me/us:

TITLE

LEACHING OF OXIDISED MOLYBDENUM 0 z FIELD OF THE INVENTION The present invention relates to the leaching of molybdenum values from ores containing 00 oxidised molybdenum.

SBACKGROUND TO THE INVENTION It is known to extract molybdenum from crushed ore by leaching with dilute sulphuric acid. Typical concentrations of sulphuric acid used are in the order to 1 to 7.5 per cent by volume. Leaching typically occurs over a period of time ranging from days through to several months.

Known methods of leaching molybdenum oxides typically have a recovery rate of about 30 to 50 percent.

The present invention attempts to provide an alternative method for leaching ofoxidised molybdenum.

SUMMARY OF THE INVENTION In accordance with one aspect of the present invention there is provided a process for leaching molybdenum from an ore containing oxidised molybdenum by treating the ore with a leaching agent comprising an acidic liquid medium containing dissolved halide ions at an elevated temperature.

O DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment of the invention the ore is crushed to a fine size, preferably to 0 Z a size less than 25 mm and more preferably to a size of about 100 to 250 microns. The size to which the ore is crushed may be varied according to economic and process factors.

00 The crushed ore is then wetted with an aqueous wetting liquid. The wetting liquid is (Ni preferably water or an aqueous solution containing dissolved halide ions such as chloride ions. The amount of wetting liquid added is preferably such that agglomeration does not take place, preferably in the range from 20 to 200 kg/ tonne of ore. The amount of wetting liquid may be varied so that there is little to no separation of liquid from the mass of ore.

The leaching agent is preferably a solution comprising halide ions and acid. The halide ions, preferably chloride ions, more preferably an aqueous solution of sodium chloride are preferably at a concentration of 0.5 to 10 per cent by weight halide salt, more preferably 1 to 6 per cent by weight, yet more preferably 2 to 3 per cent by weight. The acid is preferably a non oxidising mineral acid, more preferably sulphuric acid. The acid is preferably at a concentration of from 10 to 250 kg/ tonne of ore, more preferably 20 to kg/ tonne of ore.

The leaching agent is added to the wetted ore in an amount preferably in the range of to 200 kg/ tonne ore. The amount of leaching agent added should be such that agglomeration does not take place, or if it does, it only does so after addition of the 0 leaching agent. The amount of leaching agent may be varied so that there is little to no separation of liquid from the mass of ore.

0 The temperature of the reactants should be maintained at an elevated level throughout the leaching process, preferably at 25 0 C to 70 0 C, more preferably at 39 0 C to 00 The time required for the leaching process, the leaching time, may be between 2 hours and 72 hours, preferably between 12 and 48 hours.

In an alternative embodiment of the invention, sulphuric acid as a source for hydrogen ions may be replaced with another suitable non oxidising mineral acid, preferably hydrochloric acid.

In an alternative embodiment of the invention sodium chloride in solution may be replaced by another suitable halide, preferably by an alkali metal chloride, alkaline earth metal chloride, iron chloride, aluminium chloride or ammonium chloride.

In an alternative embodiment of the invention sodium chloride in solution may be replaced by sea water or saline ground water where the chloride ion concentration is preferably at a concentration of 0.5 to 10 per cent by weight halide salt, more preferably 1 to 6 per cent by weight, yet more preferably 2 to 3 per cent by weight.

Other oxide minerals, preferably copper oxides may be leached using the process of the present invention.

0 Molybdenum species may be recovered from the lixiviant using known techniques such as placing the agglomerated material in a heap and allowing it to cure with applications of Z the leaching solution, or in another variation by placing it on a filter belt and washing Sconcurrently to recover the soluble metal values, or in another variation dispersing the agglomerated materials in water to recover the soluble metal values by conventional 00 methods of clarification, including settling, filtering and counter current washing.

SThe present invention will now be illustrated by the following examples.

Example 1 A 1.5 kg sample of partially oxidised copper molybdenum sulphide ore was finely ground to 100 microns. Chemical analyses indicated that the ore was approximately 0.178 per cent Mo and 0.035 per cent Cu, of which 80.7 per cent of the molybdenum is present as non-sulphide material. A sufficient quantity of aqueous sodium chloride solution was then added to moisten the dry ore samples. A further solution of sodium chloride, 10 per cent by weight, and variable amounts of sulphuric acid, 10, 20 and 30 kg/ tonne ore, were then added to the moistened ore samples. The mass was agitated to ensure efficient reaction.

The temperature of the reactants were found to be in the range from 39°C to 55 0 C. The samples were maintained at these temperatures by placing in an insulated oven. The samples were cured for 2, 8 and 24 hours, after which the samples were quenched with cold tap water, diluted to a constant volume and an aliquot of each was assayed by ICP spectroscopy to determine the leaching efficiency.

It was found that the copper oxide material was completely leached in all samples. The

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extent of leaching of the oxidised molybdenum is shown in the following graph.

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Molybdenum Oxide Leaching 1600ppm Sample with 2% NaCI by weight 16 14- 24 Hour 00 12-Cnng J 10

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4 2 2 Hours curing 21 1--241 20 Kg/Tonne Ore H2SO4 It can be seen that at 2% NaCl by weight and 20 Kg/tonne or less of H 2

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4 leaching of oxidised molybdenum was almost negligible but at 30 Kg/tonne of H 2

SO

4 there was an increase in the leaching of oxidised molybdenum such as about 14% after 24 hours.

Example 2 A sample of partially oxidised copper molybdenum sulphide ore was finely ground to 100 microns. Chemical analyses indicated that the ore was approximately 0.178 per cent Mo and 0.035 per cent Cu, of which 80.7 per cent of the molybdenum is present as nonsulphide material. A sufficient quantity of aqueous sodium chloride solution was then added to moisten the dry ore samples. A further solution of sodium chloride, 3 per cent by weight, and variable amounts of sulphuric acid, 30, 40, 50 and 60 kg/ tonne ore, were then added to the moistened ore samples. The mass was agitated as in Example 1. The temperature of the reactants were found to be in the range from 39 0 C to 55 0 C. The samples were maintained at these temperatures by placing in an insulated oven. The samples were cured for 2, 8 and 24 hours, after which the sample reactions were quenched with cold tap water, diluted to a constant volume and an aliquot of each was assayed by ICP spectroscopy to determine the leaching efficiency. It was found that copper oxide material was completely leached. The extent of leaching of the oxidised molybdenum is seen in the following graph.

Oxidised Molybdenum Leach Test at 3% NaCI by weight Leach time In Hours 0--2.0 2 24 20 30 40 50 HzSO 4 KgTonne Ore It can be seen that at 3% NaCl by weight 60 Kg/tonne of H 2 SO, and a 24 hour curing time about 60% of the molybdenum was leached. Measurable results are also obtained at lower acid concentrations and lower curing times down to less than 10% leaching of molybdenum at 30 Kg/tonne H 2

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4 and a 2 hour curing time.

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Example 3 An ore containing 300 ppm of oxidised molybdenum as determined by ICP spectroscopy, was finely ground to 100 microns. A sufficient quantity of water was then added to moisten the dry ore. Various solutions of sodium chloride concentration were added with sulphuric acid, 20 kg/ tonne of ore, to the moistened ore. The samples were maintained at the heat of reaction by placing in an insulated oven. The samples were cured for 24 hours, after which the reaction was quenched with cold tap water, diluted to a constant volume and an aliquot of each was assayed by ICP spectroscopy to determine the leaching efficiency. The results are shown in the following table and graph.

[NaCI] w/w) Cu (ppm) Mo (ppm) Mo Leaching 6.73 2.05 68.2 1 7.43 2.28 75.9 8.0 2.39 79.8 2 7.07 2.61 87.1 7.12 2.55 85.0 3 6.82 2.53 84.4 6.19 2.33 77.5 4 6.16 2.32 77.3 6.55 2.01 67.1 7.61 2.36 78.7 6 7.39 2.34 77.9 0 zp 0 M

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Mo Leaching Efficiency, 300 PPM Ore Contant Acid, 20 Kg/T sulphuric add Constant Time, 24 hours 100 .0 40 -*-Mo 0.0 1.0 2.0 3.0 4.0 5.0 6.0 Percent NaCI Dry tonne of ore It can be seen that with the lower starting level of molybdenum good leaching efficiencies are achieved at NaCl concentrations in the region of 1 to 2% by weight and 20 Kg/tonne of H 2 S0 4 over a 24 hour reaction time.

Example 4 An ore containing 300 ppm of molybdenum as oxide as determined by ICP spectroscopy, was finely ground to 100 microns. A sufficient quantity of water was then added to moisten the dry ore. A solution of hydrochloric acid, 14 kg/ tonne ore, was added to the moistened ore. The sample was maintained at the heat of reaction by placing in an insulated oven. The sample was cured for 24 hours, after which the reaction was quenched with cold tap water, diluted to a constant volume and an aliquot was assayed by ICP spectroscopy to determine the leaching efficiency. The results are shown in the following table.

[HCI] (kg/ tonne Cu (ppm) Mo (ppm) Mo Leaching ore) 14 7.79 2.33 77.7 Example An ore containing 1780 ppm of molybdenum and 350 ppm copper as determined by Xray Fluorescence (XRF) spectroscopy, was finely ground to 100 microns. The lixiviant, per cent by weight sulphuric acid with varying concentrations of sodium chloride, was added to and mixed with a known weight of ore. The reaction mixture was then transferred to an enclosed vessel. The reaction mixture was subjected to a shaking treatment by a mechanical means. During this treatment the sample was maintained at the heat of reaction by placing in an insulated oven. The sample was treated for 24 hours, after which the reaction was quenched with cold tap water, diluted to a constant volume and an aliquot was assayed by XRF spectroscopy to determine the leaching efficiency.

The extent of the leaching of copper and molybdenum is shown in the following graph.

Extraction of molybdenum and copper In 20% sulphuric acid matrix 120

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020 0 5 10 15 20 25 30 Percent NaCI in Matrix It can be seen that with out sodium chloride the extraction of molybdenum from the high grade ore is negligible whereas an approximately complete extraction of the copper is achieved. At approximately 2 3 per cent by weight sodium chloride the most efficient extraction of both metal values is achieved. At sodium chloride concentrations higher than this the efficiency of the extraction declines.

Example 6 An ore containing 410 ppm of molybdenum and 530 ppm copper as determined by XRF spectroscopy, was finely ground to 100 microns. The lixiviant, 20 per cent by weight sulphuric acid with varying concentrations of sodium chloride, was added to and mixed with a known weight of ore. The reaction mixture was then transferred to an enclosed vessel. The reaction mixture was subjected to a shaking treatment by a mechanical means. During this treatment the sample was maintained at the heat of reaction by placing in an insulated oven. The sample was treated for 24 hours, after which the reaction was quenched with cold tap water, diluted to a constant volume and an aliquot was assayed by XRF spectroscopy to determine the leaching efficiency. The extent of the leaching of copper and molybdenum is shown in the following graph.

Extraction of molybdenum and copper In 20% sulphuric acid M. 0 5 10 15 20 25 30 35 40 Percent NaCI In matrx It can be seen that with out sodium chloride the extraction of molybdenum from the lower grade ore is negligible whereas an approximately complete extraction of the copper is achieved. At approximately I 4 per cent by weight sodium chloride the most efficient extraction of both metal values is achieved. At sodium chloride concentrations higher than this the efficiency of the extraction declines.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.

Claims

3. A process as defined in claim 2, wherein the chloride ions may be supplied as a solution of alkali metal chloride, alkaline earth metal chloride, iron chloride, aluminium chloride or ammonium chloride.
4. A process as defined in claim 3, wherein the chloride ions are supplied as a solution of sodium chloride. A process as defined in claim 2, wherein the chloride ions may be supplied using sea water or saline ground water.
6. A process as defined in any one of claims 2 to 5, wherein the chloride ion concentration is from 0.5 to 10 per cent by weight halide salt.
7. A process as defined in claim 6, wherein the chloride ion concentration is from 1 to 6 percent by weight halide salt.
8. A process as defined in claim 7, wherein the chloride ion concentration is 2 to 3 percent by weight halide salt. 0 z
9. A process as defined in claim 1, wherein the acid medium contains a non oxidising mineral acid. 00oO A process as defined in claim 9, wherein the non oxidising mineral acid used is sulphuric acid or hydrochloric acid.
11. A process as defined in claim 10, wherein the acid is at a concentration of from to 250 kg/tonne of ore.
12. A process as defined in claim 11, wherein the acid is at a concentration from 20 to kg/tonne of ore.
13. A process as defined in any one of the preceding claims, wherein the leaching agent is used in an amount in the range from 50 to 200 kg/tonne of ore.
14. A process as defined in any one of the preceding claims, wherein the temperature of the leaching process is in the range of from 25 to 70 'C. A process as defined in claim 14, wherein the temperature of the leaching process is in the range of from 39 to 55 'C.
16. A process as defined in any one of the preceding claims, wherein the time required for the leaching process is between 2 and 72 hours O
17. A process as defined in claim 16, wherein the time required for the leaching process is between 12 and 48 hours. 00
18. A process as defined in any one of the preceding claims, wherein the ore is crushed to a size about 100 to 250 microns.
19. A process as defined in any one of the preceding claims, wherein the ore also contains copper oxides which are also leached, along with molybdenum. A process substantially as hereinbefore described with reference to any one of the accompanying Examples.