Manganese Ore Beneficiation Process

Abstract

A process for the beneficiation of Manganese ore which includes the step of leaching of the ore with acid to remove Calcium Carbonate and Magnesium Carbonate. The ore is first broken down to the required particle size by conventional means. Selective leaching of Calcium oxide and Magnesium carbonate occurs leaving an ore having a higher Manganese content.

Claims

1. A process for the beneficiation of Manganese ore, comprising leaching of the ore with acid to remove CaCO.sub.3 (Calcium carbonate) and MgCO.sub.3 (Magnesium carbonate).

2. The process according to claim 1, wherein the ore is first broken down by one or more processes comprising crushing, milling, washing and dense media separation.

3. The process according to claim 1, wherein the ore has a particle size smaller than 100 millimetres in diameter.

4. The process according to claim 1, wherein leaching occurs by means of VAT leaching.

5. The process according to claim 1, wherein leaching occurs by means of continuous stirred tank reactor leaching.

6. The process according to claim 1, wherein leaching occurs by means of heap leaching.

7. The process according to claim 1, wherein the leaching process is a batch process.

8. The process according to claim 1, wherein the leaching process is a continuous process.

9. The process according to claim 1, wherein the process includes agitation of the acid and the ore.

10. The process according to claim 1, wherein the acid comprises hydrochloric acid.

11. The process according to claim 1, wherein the acid comprises nitric acid.

12. The process according to claim 1, wherein the acid comprises a combination of one or more of hydrochloric acid and nitric acid.

13. The process according to claim 10, wherein the acid concentration is in the range 0.1% to 100%.

14. The process according to claim 13, wherein the acid concentration is in the range 1% to 35%.

15. The process according to claim 14, wherein the hydrochloric acid concentration is in the range 2.5% to 32%.

16. The process according to claim 11, wherein the nitric acid concentration is in the range 5% to 10%.

17. The process according claim 1, wherein a Manganese content of the ore subjected to the process increases by between 5% and 30%.

18. The process according to claim 1, wherein a Calcium Oxide content of the ore decreased by up to between 16% in absolute terms and 94% in relative terms.

19. The process according to claim 1, wherein a Magnesium Oxide content of the ore decreased by up to 2.1% in absolute terms and 72% in relative terms.

Description

DESCRIPTION OF THE INVENTION

[0019] The invention will now be described with reference to the following non-limiting example.

[0020] The process for beneficiation of Manganese Ore includes providing Manganese Ore which is rich in Calcium carbonate (CaCO.sub.3) and Magnesium carbonate (MgCO.sub.3). In one embodiment of the invention, a Manganese Ore comprising 30-40% Manganese content and a 12-22% CaO content (the ore product with a size of approximately 100 mm per particle) is crushed. This product is high in CaO and MgO concentration.

[0021] The crushing of the ore product will provide a finer ore product which is then leached.

[0022] During leaching acid is added to the fine ore product. Leaching takes place by means of vat leaching and/or CSTR leaching and/or heap leaching, and these processes can be either as a batch process or a continuous process. The acid used in this process can vary, but can be hydrochloric acid and/or nitric acid. The acid used can be a combination of two or more acids at differing concentrations.

[0023] Leaching occurs at a temperature and for a length of time which ensures that an ore with a high Manganese concentration is the resultant product.

[0024] During leaching the acid added to the fine ore product will selectively leach the CaO and MgO from the fine ore product and allow for the Manganese to remain.

[0025] The leached fine ore product includes a Manganese content of 40-52% and a CaO content of 1-10%. This shows an ore product with a sufficiently decreased CaO content and with a high quality Manganese content in the Ore.

[0026] The invention therefore provides a novel process for the beneficiation of Manganese ore.

TEST RESULTS The invention is illustrated and exemplified by way of the following non-limiting tests and examples.

[0027] Three types of tests were conducted namely laboratory scale, mini-plant VAT leaching and 1 metre column leaching to illustrate heap leaching capability.

Test 1Laboratory Scale

[0028] Laboratory scale test work was carried out on 19 mm Mamatwan fines to illustrate the method. Variables tested included processing time, concentration and solid to liquid ratio.

[0029] Mamatwan ore is representative of the high Calcium carbonate and Magnesium carbonate ore, sourced from Mamatwan mine.

[0030] CaO reduces from 17% to less than 2%. The % on the graph relates to the % acid concentration used to achieve the upgrade, ranging from 2.5% to 32% hydrochloric acid.

[0031] Results obtained illustrated the following regarding the variables tested:

[0032] Timeat a constant concentration leaching (upgrading) is completed within 2 hours.

[0033] Concentrationconcentration was varied from 2.5% up to 32% with significant improvement of Mn content up to 52% from 36.5%. This was achieved with 20% HCl acid. The resultant CaO content was reduced from 17% to as low as 1%.

[0034] Solid/liquid ratio(red triangles) at a constant concentration any solid:liquid ratio above 1:>1 yields the same upgrading. All future test were conducted at a solid:liquid ratio of 1:2

Test 2VAT Leaching on a Mini-Plant Scale

Test 2a)115 mm Mamatwan Type Ore

[0035] Several tests were conducted on Mamatwan type ore (115 mm size fraction) with elemental analysis (as shown in column 1) of Mn and CaO content of 36.5% and 16.8% respectively. A VAT type leach reactor operating at 20 degrees Celsius was used for 200 kg batch sizes with approximately 400 litres of acid.

[0036] The tabulated results refer specifically to the 115 mm size fraction:

[0037] The following variables were tested during the different campaigns with HCl (hydrochloric acid): [0038] 1. Time (column 2+3)conclusion is that the majority of the upgrade is done within 2 hours of introducing the ore to the acid (lixiviant) at 5% HCl concentration. The Mn increases from 36.5% to 40.5% with a mass recovery of 83-84% and a Mn recovery of 93%. The CaO has been reduced from 16.8% to 13%. [0039] 2. Agitation (column 4)Agitation did not improve the Mn recovery nor the mass recovery of the leached product. At this scale (200 kg/batch) it seems agitation enhances the leaching of Mn in conjunction with CaOCO.sub.3. [0040] 3. Temperature (column 5)the initial temperature was increased from 20 C. to 44 C., but no real improvement has been observed in terms of Mn or mass recovery. [0041] 4. Acid concentration (column 6) was observed. At this scale (200 kg/batch) and acid concentration of 10%, significant improvement in resultant Mn content of the product was observed, increasing from 36.5% to 43.9%, although the mass recovery was only 73% and Mn recovery 88%. The CaO was reduced from 16.8% to 10.5% in the resultant ore.

[0042] Tests were also conducted with a different acid, ie HNO3 (nitric acid):tests were conducted with 5% HNO3 and 10% HNO3. Although the mass recovery was similar to the HCl tests at the same concentrations, the Mn was lower at 88% and 83% vs 93% and 88% respectively for 5% and 10% acid.

Test 2b)Fine Mamatwan Ore and Lower Grade Mamatwan Discard Ore

[0043] Several tests were conducted on finer Mamatwan type ore with elemental analysis as in the first column, Mn 35.5% and CaO 17.4% in a VAT type reactor. The table below refers specifically to the 06 mm size fraction.

[0044] The following variables were tested during the different campaigns with HCl (Hydrochloric acid): [0045] 1. Time (column 2+3)conclusion is that the majority of the upgrade is done within 2 hours of introducing the ore to the acid (lixiviant) at 5% HCL concentration. The Mn increases from 36.5% to 38-39% with a mass recovery of 80% and a Mn recovery of 86%. The CaO has been reduced from 17.4% to 14.2%. [0046] 2. Agitation (column 4)Agitation did not improve the Mn recovery nor the mass recovery of the leached product. At this scale (200 kg/batch) it seems agitation enhances the leaching of Mn in conjunction with CaOCO.sub.3. [0047] 3. Acid concentration (column 5)the concentration was increased from 5% to 10% with a little improvement in the resultant Mn content, increasing from 35.5% to 39.7%, although the mass recovery was only 75% and Mn recovery 83%. The CaO was reduced from 17.4% to 12.9% in the resultant ore.

[0048] Tests were also tests conducted with two discard products from the DMS plant, with two different Mn grades as can be seen in column 6 and 8. The ore with a size of 115 mm was treated with 10% HCl in a VAT type reactor: [0049] 1. 31.5% Mn discard ore (column 6+7)Tests were conducted for two hours at 10% acid and the Mn increased from 31.5% to 40.95, while the CaO content decreased from 22.3% to 13.6%. This with a mass recovery of 66% and Mn recovery of 86%. [0050] 2. Mn discard ore (column 8+9)tests were conducted for two hours at 10% acid and the Mn increased from 29.7% to 35.6%, while the CaO content decreased from 23.7% to 17.4%. This with a mass recovery of 68% and a Mn recovery of 81%.

Test 2c)Mamatwan Lumpy Type Ore

[0051] The lumpy ore from Mamatwan type ore was also leached in a VAT type reactor with HCl testing processing time and concentration of acid.

[0052] The results achieved are stated below: [0053] 1. Time (column 1-5)the time was varied from 2 to 24 hours with mixed results. On average the Mn increased from 36.7% to 39%, while the CaO reduced from 15.3% to 12%. The mass recovery was between 72% and 78% while the Mn recovery was between 72% an 86%. [0054] 2. Concentration (column 6)the concentration was increased from 5% to 10%, but the Mn only increased from 36.7% to 39%, while the CaO reduced from 15.3% to 13.5%. The mass recovery was 79% and the Mn recovery 84%.

[0055] A lower grade Mamatwan ore was selected to conduct heap leach tests on. Time and concentration was tested with successful upgrading of the Mn content. A 1 metre high column was used with a 300 mm diameter.

Test 3Heap Leach Tests in a 1 Metre Column With 32% Mamatwan Type Lumpy Ore

[0056] 3 heap leap tests were conducted in a 1 m column design of 300 mm diameter. The size fraction was 675 mm.

[0057] HL2the test was conducted with 5% HCl acid circulating the acid for 2.75 days

[0058] HL3the test was conducted with 10% HCl acid circulating the acid for 4.25 days

[0059] HL4the test was conducted with 10% HCl acid circulating the acid for 11 days

[0060] HL1 refers to the original ore with no leaching applied to it.

[0061] The results of this heap leaching process are shown in the table below:

[0062] HL2the Mn was upgraded from 32% to 34.3% and the CaO was reduced from 19.4% to 16.4%. The mass recovery was 85% and the Mn recovery 91%.

[0063] HL3the Mn was upgraded from 32% to 33.6% and the CaO was reduced from 19.4% to 16.0%. The mass recovery was 72% and the Mn recovery 75%.

[0064] HL4the Mn was upgraded from 32% to 40% and the CaO was reduced from 19.4% to 10.7%. The mass recovery was 69% and the Mn recovery 86%.