WO2011147868A1

WO2011147868A1 - Cementation cell for the extraction of metals from a solution

Info

Publication number: WO2011147868A1
Application number: PCT/EP2011/058553
Authority: WO
Inventors: Edmond Twite Kabamba
Original assignee: Forrest, George Arthur; Groupe Forrest International Sa
Priority date: 2010-05-25
Filing date: 2011-05-25
Publication date: 2011-12-01
Also published as: CL2012003270A1; BE1019348A5; AU2011257249A1

Abstract

Cementation room comprising at least one cementation cell provided in order to carry out a cementation of at least one first metal in at least one first aqueous phase in contact with at least one second metal in the solid state comprising: a vessel; a basket at least partially submerged in said reaction medium; a supply of said at least one first aqueous phase; at least one pneumatic supply of said at least one second metal; passing through said vessel; and an outlet of at least one second aqueous phase depleted in said at least one first metal and enriched in said at least one second metal.

Description

CEMENT CELL FOR L ¹ EXTRACTION OF METALS D ¹ SOLUTION

The invention relates to a carburizing chamber comprising one or more carburizing cells, provided for carrying out a cementation solution in at least a first aqueous phase in contact with at least one second metal, and a cementation process.

In the extractive metallurgy of non-ferrous metals, certain metals are produced as by-products of the metallurgical treatment of the main metal in the ore (see DE 3231 164, US 3655175, RU 2344185 or BE 898504). This is the case for cobalt, which is generally extracted as a by-product of the metallurgy of copper or nickel by the hydrometallurgical route. Some cobalt minerals have the disadvantage of requiring a reducing agent for their leaching of cupro-cobalt-rich ores during their hydrometallurgical treatment, whereas the copper is leached under oxidizing conditions. It is therefore interesting to develop new technologies to not only valorize copper but also cobalt and traces of uranium, silver and gold copper-cobaitiferous ores economically more profitable way. It is also interesting to develop new technologies to extract cobalt metal and cobalt salts and oxides of high purity, since they are more valuable than the carbonate salts and cobalt hydroxide currently marketed on the market. global market.

US Pat. No. 3,902,996 shows the cementation of several metals such as nickel, copper, gold, silver and platinum. Unfortunately, this document does not disclose or discuss the possibility of cobalt since cobalt is used as a cementing metal. It is also very energy consuming and suggests the addition of thiosulfate so that carburizing does not terminate prematurely.

US 3930846 discloses the precipitation of copper by iron. The invention therefore intends to provide a cementation process and a cementation room for implementing elementary metals of very high purity. This is currently only achievable by means of electrolysis. Unfortunately, such a process such as electrolysis is very energy intensive like the current hydrometallurgical processes.

In many African countries with mining potential, unfortunately, there is still a glaring deficit of electrical energy which hampers the development of the metallurgical industry and renders the current processes unusable in a reliable way. This is also the case in the Democratic Republic of Congo, particularly in the copper-cobalt province of KATANGA where the development of hydrometallurgical plants based on the electrolysis of copper and cobalt faces the lack of electrical energy in the region. Electric power generation and distribution companies sometimes face enormous financial and technical difficulties and can not meet this demand for electrical energy in a reasonably short time. it is therefore interesting to develop new technologies that consume less electrical energy than conventional processes for extraction of solvents and electrolysis on mining sites.

The present invention therefore relates to a hydrometallurgical process for cementing metals, including cobalt, which consumes less energy than the processes of the current state of the art applicable at an industrial level. To this end, the invention thus provides a cementation room provided for cementing at least a first metal in at least a first aqueous phase in contact with at least one second solid state metal, said at least one a cementation cell comprising:

a tank arranged to contain a reaction medium;

a basket arranged to be immersed at least partially in the reaction medium;

feeding the at least one first aqueous phase containing the at least one first metal, to feed the at least one first aqueous phase to the basket;

at least one pneumatic supply of at least one second metal passing through the vessel so that the at least one pneumatic supply of at least one second metal is arranged to bring the at least one first metal into contact with the at least one second metal fed pneumatically; and an outlet of at least a second aqueous phase substantially depleted in the at least one first metal and enriched in at least one second metal, connected to the vessel.

As can be seen, the present invention therefore relates to a cementation room which can operate in continuous mode, resulting in elementary metals and metal derivatives of a very high purity while being significantly less energy consuming which, unlike to electrolysis, involves the internal energy of chemical reactions. It is no longer necessary to supply external electricity to the production site to maintain hydrometallurgical conversions.

In conventional processes, since it is known that during cementation, the solution must be stirred for good reaction kinetics, cumbersome mechanical stirring means are put in place. implemented, which makes the unloading of carburizing tanks laborious and not very flexible. In the reaction vessel of the cementation chamber according to the invention, the second metal, which is more electronegative than the first metal (for example copper), is fed into the cell by pneumatic transport, which at the same time serves as a stirring vector. the solution in the cell. In this way, the reaction vessel (also sometimes called carburizing cell) is particularly well agitated compactly and the contact between the first metal to be cemented and the second metal more electronegative than the first metal is optimal. From this, it therefore results in an optimal use of the internal energy of reaction which then occurs for cementation.

Pneumatic conveying of said first metal means a metal present in a carrier gas in the form of powder, flakes, chips, granules, cables in pieces, rods, etc.

Advantageously, the carburizing room is designed to include n carburizing cells in which an n-th cementation cell comprising an n-th basket is in series with a (nl) -th cementation cell so that the (nl) -th output of an (nl) -th aqueous phase substantially depleted in the at least one first metal and enriched in the at least one second metal of the (nl) -th cementation cell is connected to the n-th supplying the (nl) -th aqueous phase to supply the (nl) -th aqueous phase to the n-th basket of the n-th cementation cell. This cascading of the carburizing cells in the carburizing room allows a great flexibility of operation when it looks like a conventional electro-wining room (EW) and then has universal parts. In addition, the carburizing room is unloaded 24h / 24h and therefore has a higher productivity than the conventional EW room. As can be seen, the cementation room comprising n cells has an operational fluidity at least equal to that of an electrolysis room to ensure an economically competitive level of productivity since the output of the (n-1) th cell or reaction vessel is connected to the input of the next, the nth cell or reaction vessel.

Advantageously, said at least one pneumatic supply is integral with said tank and not said basket while communicating with said basket.

Said at least one pneumatic supply is preferably connected to at least one diffuser, the diffuser being secured to the tank and engaged in through holes provided in the bottom of the basket. This arrangement allows to set up and freely remove the basket from the tank by sliding along the diffusers through the openings in the bottom of the basket and dimensioned for this purpose. Pneumatic agitation according to the invention therefore allows optimum agitation by the distribution of the gas by means of the diffusers in the reaction vessel of the device according to the invention. In addition, the contact between the first metal and the second metal is further improved also by the presence of the diffuser which distributes over the height and on the surface when they are present in greater numbers the second metal carried by said gas. The transport gas thus serves at the same time as a stirring vector of the solution.

In addition, the supply of said second metal is implemented by a fixed device (the diffuser is integral with the tank) and controlled which does not disturb the unloading of the tanks. The second metal more electronegative than the first metal is therefore fed preferably into the tanks by the bottom, against the current of the solution that will be fed from above. In another advantageous embodiment according to the invention, one or more baskets comprise at least one reciprocal attachment means to another attachment means arranged on a traveling crane arranged to remove said basket from said tank from above. Thus, the basket of cells is easy to recover.

In one variant, the basket comprises a surface of at least one first metal in the solid state for initiating the cementation of at least one first metal to be cements by the growth of the crystals of the at least one first metal to be cements on said surface. at least one first metal in the solid state.

In an advantageous embodiment according to the invention, the at least one second metal in the solid state is pneumatically fed into a stream of nitrogen gas, instead of air, which avoids the oxidation of the powder of said second metal.

In an advantageous embodiment according to the invention, the at least one pneumatic supply is connected to a reservoir of at least one second metal communicating with a worm for dosing at least one second metal and to a supply of gas, the gas supply being arranged to bring at least one gas, for example nitrogen gas, to the pneumatic supply where the at least one second metal is dosed by the worm.

Also, in a cementation room comprising n carburizing cells, the at least one pneumatic supply of the nth tank is connected, preferably in parallel, to the pneumatic supply of the (nl) -th vessel, each feed pneumatic is connected to a reservoir of at least a second metal and communicates with a dosing auger of at least a second metal and a gas supply, the gas supply being arranged to bring at least one gas, for example gaseous nitrogen, with pneumatic feed where said at least a second metal is dosed by the worm. Each cell is therefore preferably fed independently of the others at doses calculated and regulated for each cell.

In one variant, each case cementation cell of the cascade can in fact be regulated at the level of the gas flow and at the pneumatic supply of the said at least one second metal, thus allowing optimum recovery of the said at least one first metal of the aqueous phases of moreover. in addition depleted in said at least first metal in the cascade. The advantage of this carburizing room is that it is designed to recover an abundance of metals, that is to say to achieve a cementation of at least a first metal which is a transition metal of the periodic table. chemical elements, in particular copper, nickel, cobalt, in metallic form. In an advantageous embodiment according to the invention, the at least one second metal is a metal of the group consisting of aluminum, aluminum nitride, magnesium, iron, zinc.

The choice of at least one second metal is determined by the potential difference between the first metal / second metal pair and the desirable size of the cement crystals. By way of example, aluminum will preferably be used for reasons mentioned below, as well as for its low density which makes it a second metal of choice in a pneumatic supply.

In an advantageous embodiment according to the invention, the at least one second metal is in the form of fine particles. In this way, certain fine second metal-coated particles of cemented first metal will be able to pass through the basket and will be entrained by the aqueous phase flow in the next cell where they serve as first germs. Advantageously, the cost of the at least one second metal is balanced by recovering the at least one second metal, for example aluminum by precipitation of the solutions in the form of Al (OH) ₃ and partially in the form of Al (OH) SO ₄ , marketable in the form of alumina (AI ₂ O ₃ ) after catcination. Aluminum is available in most mining regions and this proximity facilitates the return transport of alumina to export ports.

The outlet of said at least one second aqueous phase advantageously comprises a lateral edge allowing an overflow of said at least one second aqueous phase substantially depleted in said at least one first metal.

In one advantageous embodiment according to the invention, one or more cementation cells comprise a surface of at least one second metal, for example one or more copper foils, to initiate crystallization, for example to initiate the crystallization of copper. during copper cementation on Ai. Preferably, this surface, for example this copper foil, is provided in one or more baskets to facilitate carburizing at said one or more baskets.

It can therefore be seen that the cementation room is equipped to provide the greatest possible productivity on an industrial scale, because of the synergistic function of the supply of said at least a first aqueous phase and the pneumatic supply, as well as by the permanent flow of the first aqueous phase having said at least one first metal to be cementized, and the outlet of the second aqueous phase depleted in said at least one first metal to be cementized. The fluidity of the cement salt is thus reached. Other embodiments of the carburizing chamber according to the invention are mentioned in the examples, the detailed description and the appended claims.

The present invention also relates to a method of cementing at least a first metal in at least a first aqueous phase in contact with at least one second metal in the solid state, the process comprising:

feeding to the at least one aqueous phase containing the at least one first metal in at least one first aqueous phase in a tank;

contacting at least one first metal with the at least one second metal pneumatically fed into the vessel;

a continuous cementation by the series setting of n tanks whose nth is fed by the (nl) -lower aqueous phase depleted in the at least a first metal and enriched in the at least a second solubilized metal leaving the ( nl) -th tank of at least one first metal by consumption of the internal chemical energy of the carburising reaction in the presence of at least one second solid state metal followed by depletion of the at least one aqueous phase in the at least one first metal and an enrichment of Tau at least one aqueous phase in the at least one second solubilized metal; and

recovering at least one first cemented metal in solid form.

The method according to the invention therefore makes it possible to operate in a region that has a deficit in electrical energy, as mentioned above. In order to deposit the metal according to the invention, the chemical energy internal to the reactions is used and not the external energy supplied by a rectifier as in the conventional SX / EW method. In addition, the method according to the invention makes it possible to bypass the two steps SX / EW and replace them with a single step of precipitation of copper in the form of very pure crystals. It can indeed reach a purity of 99.9% Cu. By the same treatment the solution is totally depleted in copper: final content less than 100 mg / l.

The process of the invention therefore advantageously makes it possible to treat by hydrometalurgical means ores or concentrates oxidized or sulphide of copper and cobalt to produce by cementation these two metals in the form of pure elements. Nickel, if present in the ore, with a recoverable content, can also be produced by cementation. Finally, traces of uranium can be precipitated.

The advantage of this method is therefore to recover an abundance of metals, that is to say at least a first metal selected from a transition metal of the periodic table of chemical elements, in particular copper, nickel, cobalt , silver, gold, manganese, platinum, in metallic or oxide form, or salt of acid.

Finally, we can achieve the inexpensive and profitable recovery of valuable metals such as copper and cobalt over conventional techniques. In addition, it is the first time that an industrial application of metal cementation such as cobalt and nickel is carried out continuously on aqueous phases on an industrial scale.

In an advantageous embodiment according to the invention, said at least one first metal in at least one aqueous phase comes from a prior leaching step.

The carburizing process preferably also comprises a step of initiating the cementation of at least one first metal by the crystal growth of at least a first meta! on a surface of at least a first solid metal.

In an advantageous embodiment according to the invention, the cementation process uses at least one second metal being a metal of the group consisting of aluminum, aluminum nitride, magnesium, iron, zinc.

In an advantageous embodiment according to the invention, the at least one second metal in the solid state is pneumatically fed into a stream of nitrogen gas, instead of air, which avoids the oxidation of the aluminum powder.

The choice of at least one second metal is determined by the potential difference between the first metal / second metal pair and the desirable size of the cement crystals. The price of copper has risen sharply in recent years so that Al can be economically used to cement Cu in place of iron, with the advantage of establishing a very high potential difference between pairs:

EI _Cu / Al = 0.34V - (-1.67V) = 2.01V.

This potential difference is of the same order of magnitude as the industrial voltage across the copper electrolysis cell: UA / C = 1.9 to 2.2V. Such a difference in potential makes it possible to collect the copper cement in the form of giant crystals, to exhaust the cemented aqueous phase (final concentration of the solution <100 mg / l of copper), which corresponds to a purification for copper by SX, and to ensure very fast carburizing kinetics in the sulphate medium. In fact the cementation takes place on a battery in short circuit. ΔΕ ° being much greater than 0.36V, the carburizing current is in the area of the diffusion limit current of Cu. The kinetics of cementation is then controlled by diffusion and not by the electrochemical reaction. The reaction is quasi-spontaneous. The growth of the crystals is done on the first seeds, conductive solid phase.

To deposit the metai, we therefore use the chemical energy internal to the reactions and not the external energy supplied by a transformer rectifier. Technically in the process according to the invention, the copper is deposited by cementation on the aluminum powder according to the reaction:

3Cu ⁺⁺ + 2AI ° = 3Cu ° + 2AI ³⁺

3CuSO _{4 (aq)} + 2AI ° _(S) = 3Cu ° _(s) + AI ₂ (SO ₄ ) ₃ (aq)

ΔΘ ° 298 = -278.73 kcal.

Moreover, the copper being very electropositive compared to the other elements present in the solution, it precipitates alone, without possible contamination. The low stoichiometric excess of Al is consumed by secondary reactions such as Fe ²⁺ / Fe ³⁺ and acid attack. To avoid simultaneous precipitation of aluminum hydroxide [Al (OH) ₃ ], the pH of the solution will be advantageously controlled at pH = 2.5. It is thus possible to obtain a 99.9% Cu titrant copper after thorough washing to remove the impregnating sulphate solution.

The cementation by iron or zinc leads to a very fine powdery cement which is easily oxidized in the air and is polluted by iron or zinc, the potential difference between the couples being relatively weak to lead to a cement under form giant crystals. Moreover, the exhaustion of the solution is not always very thorough.

The other advantage and not least is the difference in valences and molecular weights between Al and Cu which leads to low Al consumption per tonne of Cu. In fact, the theoretical consumption of Al per ton of cemented copper is:

2 x 27/3 x 63.55 = 0.283 T of Al per T of Cu. From the point of view of economic profitability, this aspect of the question is one of the fundamental criteria in the choice of AI as a copper cementation metal among other metals.

Other embodiments of the cementation process according to the invention are indicated in the appended claims.

The present invention also relates to a use of a hydrometallurgical reactor according to the invention for upgrading a metal ore (oxidized or sulphured), its concentrate or its ashes for roasting sulphides. Other embodiments of the use of a hydrometallurgical reactor according to the invention are indicated in the appended claims.

Other features, details and advantages of the invention will emerge from the description given below, without limitation and with reference to the accompanying drawings and examples.

Figure 1 is a graph showing a carburizing room, according to the invention.

Figure 2A is a graph showing a carburizing cell according to the invention. Figure 2B is a schematic section of a cementation cell according to the invention.

Figure 3 is an assembly drawing showing two carburizing cells connected in series according to the invention.

Figure 4 is a graph showing a diffuser according to the invention.

Figure 5 is a diagram of a cementation implemented in the cementation room according 1'invention. In the figures, identical or similar elements bear the same references.

For the purposes of the invention, the term "metal ore" is intended to mean polymetallic ores, including, inter alia, those of the Shinkolobwe type or deposits of Swampo, Kasompi, or Musonoi, uranium-poor polymetallic ores and cupro ores. - cobaltifer like among others of the belt of Katanga characterized by the presence of traces of uranium. For the purposes of the invention, the term "metal ore" also refers to oxidized ores, which are often occuring at the surface of the deposit and sulphide ores, rather occurrently at depth. This metal ore may be an ore that includes U, Cu, Co, Ni, in the presence of traces of noble metals such as Au, Ag and platinoids.

FIG. 1 thus illustrates a cementation room 100 comprising at least one or more cementation cells 300 provided for cementing at least one first metal in at least one first aqueous phase in contact with at least one second metal.

As can be seen in FIG. 1, the cells 300 can be cascaded in rows in the carburizing room 100 so that the upper cell feeds the next lower cell. The aqueous phase containing one or more metals to be cements can be stored in a tank 102 from which the first cell 300 is fed.

The carburizing room 100 has a distribution network 104 of the second carburising metal in a gaseous flow, for example Al powdered in a stream of nitrogen gas. The second carburising metal may be stored, for example in a tank 105. Each cell 300 is then equipped with a pneumatic supply for pneumatically dosing this second carburizing metal in the medium. reaction to carry out the cementation, for example cementation of copper. An adequate dosage of the Al powder can be carried out in each cell by flow rate regulators, for example worms 106. The powdered Al is thus blown into one or more cells 300 by a gas blast 107, for example, a flow of nitrogen gas.

In addition, the carburizing room 100 may include a crane 101 designed to remove the baskets of cells, for example baskets filled with one or more elements. In a particular embodiment of the invention, a column of four cells is discharged at a time. Thus, 6 unloading cycles can be obtained per cell and per day.

The carburizing room 100 may further comprise elements for treating the final products of the carburizing process. Thus, a depletion tank 108 may be provided to contain the last aqueous phase. The elements obtained can in turn be washed in a rinsing station of the elements 109, before being transported to storage by means of transport 110. To recover the fines from the elements, for example from the last aqueous phase, a pump 1 1 can facilitate transportation to a filtration means. The carburizing room 100 may further include a work floor 112 between the rows.

As the carburizing room is designed to operate on an industrial scale, its dimensions are suitable for this treatment of large volumes of liquids. In a particular embodiment of the invention, the dimensions presented in Table 1 are envisaged: Table 1.-

In another particular embodiment of the invention, the carburizing room is configured in four halls of sixteen cells each,

Arranged in columns and cascaded rows of four by four.

Each hall is equipped with a traveling crane (± 7.5 T). The room is thus equipped with 64 carburizing cells, which with an average load of one ton per basket and 6 cycles per day, can produce up to 12.128 tons. The average daily production is therefore 307.2 tons.

For example, for a first aqueous phase titrating 40 g / l Cu, the flow rate of the aqueous phase per row is 25m ³ / h. Unlike the conventional EW room, the unloading of a carburizing room can be done 24 hours a day. The total area of the hall can thus be set at 65 mx 25 m = 1625 m ² .

We can notice that the same room can produce twice its capacity, that is to say 200,000 tons of copper per year, if we enrich the 50 g / l Cu solution and increase the flow rate of the solutions to 35 m ³ / h. This is only possible in a carburizing room and not in EW.

As can be seen in FIGS. 2A, 2B and 3, the cementation cell 200 comprises a tank 201 arranged to contain a reaction medium 202.

Depending on the reactions to be implemented in the tank 201, it may be fiberglass, stainless steel, or electrically isolated from the aqueous phase such as carbon steel, optionally protected by an anti-acid resin coating , as well as all moving and static parts that are present.

In a particular embodiment of the invention, the tank 201 is fed by a feed 203 from the top and emptied by an outlet 204 through the bottom. The tank 201 can also be fed from the top and emptied from the top. In another advantageous embodiment of the invention, the cementation cell 200 comprises a basket 205 arranged to be immersed at least partially in the reaction medium. The basket 205 is arranged to receive the at least one pneumatic supply 206, for example through openings in the bottom of the basket 207. The basket 205 may be perforated with fine holes 208, for example from 2 to 3 mm so as not to leave pass giant crystals of copper. Basket 205 may be placed on seats 209, for example fixed seats inside the tank.

The carburizing room 100 is preferably equipped with a system for distributing the aqueous phases on the different rows. The valve-registers at the inlet 212 and at the outlet 213 of each cell 200 regulate the flow rate of the solutions in order to keep the level in each tank 201 constant. This level is flush with the basket. 205 while maintaining a safety guard at the level of the tank 201. In case of total blockage of the basket by the elements, it can thus overflow on the side edges 203, 204, 212, 213 of the basket in the tank, without loss of solutions out of the cell circuit. The basket 205 has a surface 210 of at least a first metal for initiating cementation of the metal to be cemented by the growth of the crystals of the metal to be cemented on the sheet of first metal. For example a copper sheet 210 more or less rough, can be placed in the bottom of the basket 205 on four feet so as not to impede the flow of the solution.

The basket 205 has dimensions such that it does not touch the bottom and the walls of the tank 201 to circulate the aqueous phase through the basket. The aqueous phase fed from above through an orifice 203 formed in a wall of the tank, can pour completely into the basket and can be collected in the bottom of the tank through the outlet 204 after passing through the basket. The solution thus collected feeds the next cell. The basket may be provided with handles 21 1 which can be hooked by the rudder of a crane 01 (see Fig. 1) to place it in or out of the tank 201.

The cementation cell 200 further comprises a feed 203 of said aqueous phase containing said at least one first metal in solution, to supply the at least a first aqueous phase in the basket. The cementation cell 200 comprises at least one pneumatic supply 206 of at least one second metal, connected to the basket 205 and passing through the tank 201 so that the pneumatic supply

206 is integral with the tank and not the basket while ending in the basket. The pneumatic supply also includes a diffuser As explained in more detail in FIG. 4, each case cementation cell of the cascade may be regulated at the level of the gas flow and at the pneumatic supply of the at least one second metal by a flow control means 212, 213. Cementation cells will be dimensioned so that the handling of the baskets is not too laborious and cumbersome. The traversal speed of the solution through the basket is relatively low so as not to pull the nucleons out of the basket before they grow. The celluies will have the following external dimensions presented in Table 2.

Table 2.-

As can be seen in Figure 4, the pneumatic supply comprises at least one diffuser 400 which comprises a nonreturn valve 402 and a sealed cap 403 rotating around the diffuser and drilled eccentric holes. The supply lines 401 of aluminum powder in the cell 200 pass through the tank by sealed passages and release the aluminum powder and stirring gas at half height in the basket. These pipes, four per basket, are arranged at the four corners of the basket, a little behind the walls of it. The basket is itself provided with four holes 207 through which the pipes freely pass. These diffuser pipes 400 (or disperser 400 of aluminum powder) are therefore integral with the tank and not the basket. This arrangement allows to set up and remove freely the basket of the tank by sliding along the pipes-diffusers through the holes 207 arranged in the bottom of the basket and sized for this purpose.

The invention also relates to a cementation process which is preferably integrated in a treatment process particularly suitable for ores of the Democratic Republic of Congo. The process will therefore be described as being integrated into the overall copper-cobaltifer ore processing process, knowing that the latter can of course be implemented separately or in another overall process of ore processing as needed. The copper-cobalt-rich ore is therefore first subjected to oxidative leaching for copper and reducing to cobalt 601 from which the copper-containing aqueous phase is separated from the pulp to form a cementation in a subsequent step 602. copper on aluminum. The aqueous phase containing the copper also contains iron, manganese, cobalt and magnesium.

After clarification of the solution of its oxidative leaching, the copper is produced by cementation on the aluminum powder in the cementation room according to the invention, according to the reaction: 3Cu ^{2 ÷} + 2ΑΓ = 3Cu ° + 2Al ^{3 ÷}

3CuS0 _{4 {aq)} + 2AI ° _(S) = 3Cu ° _(s) + AI ₂ (S0 ₄ ) ₃ <a _q)

AG ^û _React. 298 = - 278.73 Kcal

AE ° _react . 298 = 2.014V. This potential difference of the same order of magnitude as the industrial voltage at the terminals of the copper EW cell (U _A C = 1, 9-2.2 V) thus makes it possible, as mentioned above, to collect the copper cement in the form of of giant crystals, to exhaust the cemented solution (final concentration of the solution <100 mg / l). This corresponds to a purification for copper by SX and to ensure very fast carburizing kinetics in sulfuric medium.

Therefore, during the cementation of the copper 602, the copper present in a first oxidation state (+1, +2) passes to the second oxidation state (0) in contact with the second more electronegative metal (for example aluminum) and precipitates.

Copper being very electro-positive compared to the other elements present in the solution, it precipitates alone without possible contamination. The small excess of aluminum is consumed by parasitic reactions such as Fe ²⁺ / Fe ³⁺ and acid attack. To avoid simultaneous precipitation of Al (OH) ₃ , the pH of the solution is maintained at pH = 2 - 2.5. It is thus possible to obtain a 99.9% Cu titrant copper, after thorough washing to remove the impregnating sulfate solution.

The dosed aluminum powder is fed into the cell by pneumatic transport by nitrogen gas, which at the same time serves as a vector for stirring the solution in the cell.

For reasons of safety (flammability of aluminum powder), aluminum nitride (AIN) powder can be used instead of aluminum. But in this case ΔΕ ° drops to ΔΕ ° = 1, 285V. The copper cements will be melted to be cast into ingots.

The solid copper is thus recovered while the aqueous phase is further treated to precipitate and remove impurities such as iron and manganese by oxidation with a mixture of air and SO ₂ in a suitable reactor. Iron and manganese are recovered as solid oxide or hydroxide while the aqueous phase is further treated to recover the aluminum in step 604. This step comprises neutralization of the aqueous phase with a base to precipitate water. aluminum hydroxide, recover it and then calcine it to form alumina.

The aqueous phase can then be treated for the recovery of cobalt, either by precipitation 605 or by cementation 610.

The aqueous phase is then subjected to oxidation, for example by a gaseous air / S0 ₂ mixture which produces Co 0 ₃ cobaltic oxide from Co (OH) ₃ obtained from the cobalt sulfate initially present in the phase. aqueous. The pH of the aqueous phase is advantageously between 5 and 6, after neutralization by addition of a basic solution or suspension, for example by adding milk of magnesia so as not to pollute the precipitate. Generally, the nickel present in the aqueous phase in trace form will not be oxidized before cobalt. If the aqueous phase contains more nickel, it will be necessary to add a preliminary purification step to remove the nickel.

The CO 2 O 3 salt is recovered by decantation, filtration, filter-press washing and is then calcined and conditioned for its recovery.

The aqueous phase substantially depleted of cobalt is rich in magnesium. High concentration magnesium salts are generally harmful to the environment. This aqueous phase is thus treated by addition of a basic solution or suspension, for example by addition of limestone or lime milk which allows the precipitation of Mg (OH) ₂ at a pH of preferably> 10 (606). The solid Mg (OH) ₂ present in the +2 oxidation state is recovered and can be reused as a neutralizer in the solution / basic suspension. Otherwise, the Mg (OH) ₂ is released separately or simultaneously with the leaching releases. The magnesium-depleted aqueous phase can then be further treated to plump solid discharges or ore at leaching step 601. Otherwise, the aqueous phase can be further treated for uranium recovery when present. (607). If the aqueous phase resulting from the precipitation step of aluminum 604 is treated to recover the cobalt by carburizing 610, optionally with the addition of a solution / basic suspension, for example milk of magnesia to promote the kinetics of reaction.

The cobalt thus case hardened (optionally together with aluminum and magnesium) is thus recovered and the aqueous phase is then optionally treated to precipitate aluminum hydroxide 611 in the presence of a base before treating the wastewater with water. step 608.

The cobaltic hydroxide precipitated in step 605 can be relixed in a sulfuric medium and in the presence of S0 ₂ . SO2 is, in this case of relixiviation pure oxide precipitates C02O3.XH2O, as a non-polluting reducing agent for the solution. In the absence of the Fe ²⁺ / Fe ³⁺ oxidation-reduction pair, the cobalt reagents are reacted according to the following reactions: 2 [Co (OH) ₃ ] _s + [S0 ₂ ] _aq + [H ₂ SO ₄ ] _aq = 2 [CoS0 ₄ ] _aq + 4 [H ₂ 0],

2 [CoOOH] _s + [S0 ₂ ] _aq + [H ₂ S0 ₄ ] _aq = 2 [CoS0 ₄ ] _aq + 2 [H ₂ 0],

[Co ₃ 0 ₄ ] _s + [S0 ₂ ] _aq + 2 [H ₂ S0 ₄ ] _aq = 3 [CoSO ₄ ] _aq + 2 [H ₂ 0] _t

[Co ₂ 0 ₃ ] _s + [S0 ₂ ] _aq + [H ₂ S0 ₄ ] _aq = 2 [CoSO ₄ ] _aq + [H ₂ O],

The relixed cobalt of step 609 may after cementation 610 to obtain cobalt metal in very high purity. The waste water is then also treated 608 and neutralized with limestone (filler) and lime milk to precipitate Mg (OH) ₂ at pH> 10. After decantation and filtration, the clear water can be recycled in the process. After solid / liquid separation, the solids, if not reused as a neutralizer in another process step, are discharged separately or at the same time as the leaching releases.

It is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made without departing from the scope of the appended claims.

Claims

claims

Characterized in that it comprises at least one cementation cell provided for cementing at least one first metal in at least one first aqueous phase in contact with at least one second metal in the solid state, said at least one cementation comprising:

a tank arranged to contain a reaction medium;

a basket arranged to be immersed at least partially in said reaction medium;

feeding said at least one first aqueous phase containing said at least one first metal, to supply said at least one first aqueous phase to said basket;

at least one pneumatic supply of said at least one second metal, passing through said tank such that said at least one pneumatic supply of said at least one second metal is arranged to bring said at least one first metal into contact with said at least one second pneumatically powered metal; and

an outlet of at least a second aqueous phase substantially depleted of said at least one first metal and enriched in said at least one second metal, connected to said tank.

A cementation chamber according to claim 1 comprising n carburizing cells in which an n-th cementation cell comprising an n-th rack is in series with a (nl) -th cementation cell such that the (nl) -th leaving an (nl) -th aqueous phase substantially depleted of said at least one first metal and enriched in said at least one second metal of said (nl) th carburizing is connected to the n-th feed of the (nl) -th aqueous phase to supply said (nl) -th aqueous phase to said n-th basket of said n-th cementation cell.

3. A carburizing chamber according to claim 1 or 2 wherein said at least one pneumatic supply is integral with said tank and not said basket while communicating with said basket.

4. A carburizing chamber according to any one of claims 1 to 3 wherein said at least one pneumatic supply is connected to a reservoir of said at least one second metal communicating with a dosing worm of said at least one second metal; and a gas supply, said gas supply being arranged to bring said gas to the pneumatic supply where said at least one second metal is dosed by said worm.

5. A carburizing chamber according to any one of claims 1 to 4 wherein said at least one pneumatic supply is connected to at least one diffuser, said diffuser being secured to said tank and engaged in through holes provided in the bottom of the basket .

6. A carburizing chamber according to any one of claims 2 to 5 wherein said at least one pneumatic supply of the n-th vessel is connected, preferably in parallel, to the pneumatic supply of the (nl) -th vessel, each pneumatic supply is connected to a reservoir of said at least one second metal and communicates with a dosing worm of said at least one second metal and a supply of nitrogen gas arranged to bring said nitrogen gas to the pneumatic feed where said at least one second metal is dosed by said worm,

7. A carburizing chamber according to any one of claims 1 to 6, wherein said at least one first metal is a transition metal of the periodic table of chemical elements, including copper, nickel, cobalt, silver. , gold, manganese, platinum, in the form of oxide or salt of acid.

8. A carburizing salt according to any one of claims 1 to 7 wherein said at least one second metal is a metal selected from the group consisting of aluminum, aluminum nitride, magnesium, iron, zinc .

9. A cementation room according to any one of claims 1 to 8 wherein said gas is nitrogen. 10. A carburizing chamber as claimed in any one of claims 1 to 9, wherein at least one surface of at least one first solid state metal is present in a reaction vessel.

11. Salie carburizing according to any one of claims 1 to 10, wherein said basket comprises at least one reciprocal attachment means to another attachment means arranged on a traveling crane arranged to remove said basket from above. said tank.

12. A method of carburising at least a first metal in at least a first aqueous phase in contact with at least one second metal in the solid state, said process comprising:

a supply of said at least one aqueous phase containing said at least one first metal in at least one first aqueous phase in a tank;

contacting said at least one first metal with said at least one second pneumatically fed metal in said tank;

continuous carburizing by placing in series n vessels whose nth is fed by said (nl) -th aqueous phase depleted in said at least one first metal and enriched in said at least one second solubilized metal leaving the (nl the second tank of said at least one first meta! by consumption of the internal chemical energy of the carburizing reaction in the presence of said at least one second metal in the solid state followed by depletion of said at least one aqueous phase in said at least one first metal and enrichment at least one aqueous phase of said at least one second solubilized metal; and

recovering said at least one first cemented metal in solid form.

13. The carburizing method according to claim 12 wherein said at least one first meta! is a transition metal of the periodic table of chemical elements, including copper, nickel, cobalt, silver, gold, manganese, platinum, oxide, or acid salt.

The cementation method of claim 12 or 13, wherein said at least one second metal is a metal of the group consisting of aluminum, aluminum nitride, magnesium, iron, zinc.

15. The method of cementation according to any one of claims 12 to 14, wherein said at least a first metal in at least one aqueous phase comes from a previous step of iixiviation.

The carburising method according to any one of claims 12 to 15 wherein said at least one second solid state metal is pneumatically fed into a stream of nitrogen gas.