Title of Invention

A PROCESS FOR RECOVERY OF METALS FROM A MIXTURE OF MANGANESE NODULE AND A MINERAL ORE.

Abstract

The present invention relates to a process for recovery of metals from a mixture of manganese nodule and a mineral ore. The process steps are: leaching of a manganese nodule characterized in that in hydrochloric acid medium in the presence of a mineral ore selected from chalcopyrite and sphalerite at atmospheric pressure and a temperature ranging between 20 to 35°C to bring the metals into solution, filtering the resulting slurry to obtain a leach liquor containing the chlorides of copper, zinc, manganese, iron, nickel and cobalt, recovering the desired metals by known methods.

Full Text

The present invention relates to a process for recovery of metals from a mixture of manganese nodule and a mineral ore. This invention more particularly relates to a process for the recovery of copper, nickel, cobalt, manganese and other metal values as their chlorides from deep-sea manganese nodule, and copper from chalcopyrite (copper concentrate) and zinc from sphalerite through leaching of the mixture in hydrochloric acid. Manganese nodules are accretions of intimately mixed metal oxides, principally manganese dioxide and iron oxide (goethite) and are available on the ocean bed at a depth of 4 to 6 kilometres. A number of other valuable metals, in particular Ni, Co, Cu, Mo, Zn and V, are also present in the nodule in appreciable quantities. Therefore, a considerable amount of interest has been shown in manganese nodule as a potential source of the aforesaid metals and a large number of patents have been granted for processes designed to extract metals from it. Reference may be made to various processes developed for recovery of metal values from manganese nodule, that can be classified into three categories on the basis of the lixiviant used in the process [Benjamine, W. Haynes, Stephen L. Law and Riki Maeda (1983). Updated process flow sheets for manganese nodule processing. USBM Information Circular IC 8924] the lixiviants being (i) Ammonia (ii) Sulphuric acid and (iii) Hydrochloric acid. The first two lixivants are associated with the disadvantage that they recover only three metals i.e. Cu, Ni and Co whereas in the HC1 based process Mn is also recovered in addition to the above mentioned metals. One of the disadvantages of the reduction and HC1 leach process is that it involves a roasting step which may require more energy. Dissolution of manganese nodule is usually accomplished in the presence of a reducing agent. Though various process routes have been attempted using different reductants to dissolve the manganese oxide, no attempt has been made to leach a mixture of nodule and chalcopyrite (an oxidant-reductant combination). The present process is the outcome of one such effort. A process developed by a Belgian Company, Metallurgie Hoboken Overpelt (MHO) [Van Peteghem, A. L., US Patent 4,026,773, 31 May 1977] ' uses a strong HC1 solution as a leachanf for the crushed nodule following the reaction: Mn02 + 4 HC1 = MnCl2 + 2 H2O + C12 Most of the other metal values like Ni, Cu, Co etc., also dissolve. This process does not include any chalcopyrite during leaching. The present process adds chalcopyrite with certain advantages as outlined below. The main drawbacks of the prior art are that chalcopyrite and sphalerite does not dissolve easily in dilute mineral acids and requires an oxidizing agent for its dissolution. Both chalcopyrite and sphalerite are semiconductors having a low resistivity and sets up a rest potential when in contact with an electrolyte. It has been established that the oxidative dissolution of chalcopyrite and sphalerite follows the principle of corrosion. When present together, MnO2 and chalcopyrite sphalerite form a galvanic corrosion couple which results in enhanced dissolution of both the minerals through galvanic interaction. The main object of the present invention is to provide a process for the recovery of metals from a mixture of manganese nodule and chalcopyrite sphalerite which obviates the drawbacks as detailed above. Another object of the present invention is to provide a novel process for the dissolution of manganese nodule and chalcopyrite or sphalerite with consumption of less energy and in shorter time. The production of copper was almost doubled when only 5 g chalcopyrite was added to 100 g of manganese nodule. Accordingly, the present invention provides a process for the recovery of metals from a mixture of a manganese nodule and a mineral ore which comprises; leaching of a manganese nodule characterized in that in hydrochloric acid medium in the presence of a mineral ore selected from chalcopyrite and sphalerite at atmospheric pressure and a temperature ranging between 20 to 35°C to bring the metals into solution, filtering the resulting slurry to obtain a leach liquor containing the chlorides of copper, zinc, manganese, iron, nickel and cobalt, recovering the desired metals by known methods. In an embodiment of the present invention the particle size of the reacting minerals used is upto 150µm. In yet another embodiment of the present invention the dissolution of manganese and mineral ore take place at atmospheric pressure and a temperature ranging between 20 to 35 °C. In accordance with the process of the present invention, the presence of manganese nodule enhances the dissolution of chalcopyrite sphalerite considerably. This may be because of two electrochemical pathways of dissolution such as corrosion coupling due to cyclic action of a redox couple (generated from the impurities of the ore) and galvanic interaction. Further, chlorine generated in the system also plays a role in the dissolution of chalcopyrite or sphalerite. Thus, the present invention provides a process where the manganese in the nodule dissolves at a faster rate with simultaneous dissolution of chalcopyrite or sphalerite producing a liquor of much higher copper content (coming from both manganese nodule and chalcopyrite) or zinc content (coming from both manganese nodule and sphalerite) which will add to the final product value. The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention. Example 1 20 g Mn-nodule (20% Mn, 0.953 % Cu, 1.01% Ni, 0.1% Zn, 0.14 % Co, 7.77% Fe ) of -75 µm particle size containing 4 g Mn, 0.1906 g Cu, 0.202 g Ni, 0.02 g Zn, 0.028 g Co, 1.554 g Fe was reacted with 100 ml of 4M HC1 in a 500 ml Corning beaker for one hour at room temperature (30° C). 1.007 g Mn, 0.14 g Cu, 0.08 g Ni, 0.013 g Zn, 0.008 g Co and 0.804 g Fe could be brought into solution. Again 5 g chalcopyrite (21.05% Cu) of-75µm particle size containing 1.05 g of copper was reacted with 100 ml of 4 M HC1 in a 500 ml Corning beaker for half an hour at room temperature. 0.085 g copper could be brought into solution. But when 20 g of the same manganese nodule and 5 g of same chalcopyrite both of -75 µm particle size, the former containing 4 g Mn, 0.1906 g Cu, 0.202 g Ni, 0.02 g Zn, 0.028 g Co, 1.554 g Fe and the latter containing 1.05 g Cu respectively were reacted in a 500 ml coning beaker with 100 ml of 4 M HC1 for one hour at room temperature, 0.581 g of copper and 2.65 g Mn could be brought into solution. 0.143 g of Ni, 0.015 g Zn, 0.016 g Co 1.284 g of Fe were also leached in addition to copper and manganese. Example 2 40 g Mn-nodule (20% Mn, 0.953 % Cu, 1.01% Ni, 0.1% Zn, 0.14 % Co, 7.77% Fe) of -75 µm particle size containing 8 g Mn, 0.3812 g Cu, 0.404 g Ni, 0.04 g Zn, 0.056 g Co, 3.108 g Fe and 5 g chalcopyrite (21.05% Cu) containing 1.05 g Cu was reacted with 400 ml of 4M HC1 in a 500 ml Corning beaker for one hour at room temperature (30° C). 1.11 g of Cu and 7.38 g of Mn could be brought into solution. Simultaneously 3.035 g of Fe, 0.436 g Ni, 0.039 g Zn, 0.046 g Co were also leached. Example 3 A mixture of 20 g Mn-nodule (20% Mn, 0.953 % Cu, 1.01% Ni, 0.1% Zn, 0.14 % Co, 7.77% Fe) and 5 g chalcopyrite (21.05% Cu) both of-75 µm particle size and containing 4 g Mn, 0.1906 g Cu, 0.202g Ni, 0.02g Zn, 0.028g Co, 1.554g Fe and 1.05 g of Cu was reacted with 100 ml of 5 M HC1 in a 500 ml Corning beaker for one hour at room temperature. 0.741 g of Cu and 3.714 g of Mn was leached. 0.213 g of Ni, 0.018 g Zn, 0.02 g Co and 1.726 g Fe also came into solution. Example 4 5 g Mn-nodule (20% Mn, 0.953 % Cu, 1.01 % Ni, 0.1 % Zn, 0.14 % Co, 7.77 % Fe) of -75 µm particle size containing 1 g Mn, 0.04665 g Cu, 0.0505 g Ni, 0.005 g Zn, 0.007 g Co, 0.3885 g Fe was reacted with 100 ml of 4 M Hcl in a 500 ml coming beaker for one hour at room temperature (300 C). 0.781 g Mn, 0.038 g Cu, 0.047 g Ni, 0.004 g Zn, 0.0032 g Co and 0.198 g fe could be brought into solution. Again 2 g sphalerite (46.68 % Zn) of -75 µm particle size containing 0.9336 g of zinc was reacted with 100 ml of 4 M Hcl in a 500 ml corning beaker for one hour at room temperature. 0.087 g zinc could be brought into solution. But when 5 g of the same manganese nodule and 2 g of same sphalerite both of -75 µm particle size, the former containing 1 g Mn, 0.04676 g Cu, 0.0505 g Ni, 0.005 g Zn, 0.007 g Co, 0.3885 g Fe and the latter containing 0.9336 g Zn respectively were reacted together in a 500 ml coning beaker with 100 ml of 4 M Hcl for one hour at room temperature, 0.476 g of zinc and 0.993 g manganese could be brought into solution. 0.038 g of Ni, 0.0043 g Co, 0.044 g of Cu and 1.284 g of Fe were also leached in addition to zinc and manganese. Example 5 15 g of Mn-nodule (20 % Mn, 0.953 % Cu, 1.01 % Ni, 0.1 % Zn, 0.14 % Co, 7.77 % Fe) of -75 µm particle size containing 3 g Mn, 0.1429 g Cu, 0.1515 g Ni, 0.015 g Zn, 0.021 g Co, 1.1655 g Fe and 2 g sphalerite (46.68 % Zn) containing 0.9336 g Zn was reacted with 100 ml of 4 M Hcl in a 500 ml corning beaker for one hour at 60 C. 0.879 g of Zn and 2.883 g of Mn could be brought into solution. Simultaneously 1.039 g of Fe, 0.21 g Ni, 0.132 g Cu, 0.013 g Co was also leached. Example 6 A mixture of 15 g Mn -nodule (20 % Mn, 0.953 % Cu, 1.01 % Ni, 0.1 % Zn, 0.14 % Co, 7.77 % Fe) and 6 g sphalerite (46.68 % Zn) both of -75 µm particle size and containing 3 g Mn, 0.1429 g Cu, 0.1515 g Ni, 0.015 g Zn, 0.021 g Co, 1.1655 g Fe and 2.8008 g of Zn was reacted with 100 ml of 4 M Hcl in a 500 ml corning beaker for one hour at room temperature. 1.085 g of Zn and 2.675 g of Mn was leached. 0.153 g of Ni, 0.123 g Cu, 0.016 g Co and 1.155 g Fe also came into solution. The main advantages of the process of the present invention are 1. Manganese, nickel, copper, cobalt from manganese nodule and copper from chalcopyrite or zinc from sphalerite are brought into solution without producing sulphur dioxide so that the process is environment friendly. 2. The dissolution process takes place at room temperature, atmospheric pressure and uses dilute hydrochloric acid using up all the chlorine evolved to dissolve chalcopyrite and therefore, can be accomplished in simple reactors. 3. Dissolution of manganese from the nodule takes place at a faster rate in identical HC1 solution in presence of CuFeS2 than in absence of it which results in saving of reaction time, energy consumption and reactor size. 4. Copper dissolving form chalcopytite adds value to the final product. 5. Zinc dissolving from sphalerite adds value to the final product. We Claim: 1. A process for the recovery of metals from a mixture of a manganese nodule and a mineral ore which comprises; leaching of a manganese nodule characterized in that in hydrochloric acid medium in the presence of a mineral ore selected from chalcopyrite and sphalerite at atmospheric pressure and a temperature ranging between 20 to 35°C to bring the metals into solution, filtering the resulting slurry to obtain a leach liquor containing the chlorides of copper, zinc, manganese, iron, nickel and cobalt, recovering the desired metals by known methods. 2. A process as claimed in claim 1, wherein the particle size of the minerals ore used is upto 150 µm. 3. A process for the recovery of metals from a mixture of a manganese nodule and a mineral ore substantially as herein described with reference to the examples.

Documents:

111-del-2001-abstract.pdf

111-del-2001-claims.pdf

111-del-2001-correspondence-others.pdf

111-del-2001-correspondence-po.pdf

111-del-2001-description (complete).pdf

111-del-2001-form-1.pdf

111-del-2001-form-19.pdf

111-del-2001-form-2.pdf

111-del-2001-form-3.pdf