Field of the invention

The invention relates to a method for refining copper concentrate as defined in the preamble of independent claim 1.

The invention also relates to an arrangement for refining copper concentrate as defined in the preamble of independent claim 14.

The method includes using a suspension smelting furnace and the arrangement comprises a suspension smelting fumace. With a suspension smelting fumace is in this context meant for example a direct to blister furnace or a flash smelting furnace.

Figure 1 show an arrangement for refining copper concentrate 1 according to the prior art. The arrangement shown in figure 1 comprises a suspension smelting furnace 2, a slag cleaning furnace 3 in the form of an electrical furnace, and anode furnaces 4. The suspension smelting furnace 2 comprises a reaction shaft 5, a settler 6, and an uptake 7. The reaction shaft 5 of the suspension smelting furnace 2 is provided with a concentrate burner 8 for feeding copper concentrate 1 and additionally at least reaction gas 9, and preferable also flux 10, into the reaction shaft 5 of the suspension smelting furnace 2 to obtain a blister layer 11 containing blister and a first slag layer 12 containing slag on top of the blister layer 11 in the settler 6 of the suspension smelting furnace 2. The slag cleaning furnace 3 is configured for treating slag fed from the settler 6 of the suspension smelting furnace 2 slag with a reduction agent 13 to in the slag cleaning furnace 3 obtain a bottom metal layer 14 containing bottom metal copper and a second slag layer 15 containing waste slag on top of the bottom layer 14. The arrangement shown in figure 1 comprises additionally slag feeding means 16 for feeding slag from the first slag layer 12 settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3. The arrangement shown in figure 1 comprise additionally blister feeding means 18 for feeding blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 to the anode furnaces 4. The arrangement shown in figure 1 comprises additionally bottom metal feeding means 19 for feeding bottom metal copper from bottom metal layer 14 in the slag cleaning furnace 3 to the anode furnaces 4. The arrangement shown in figure 1 comprises additionally waste slag discharging means 20 for discharging waste slag 21 from the slag cleaning furnace 3. The arrangement shown in figure 1 comprises additionally anode casting molds 17 for casting copper anodes (not shown in the figures) which can be used in an electrolytic refining process for further refining of the bottom metal copper.

One problem with a prior art arrangement as shown in figure 1 is that if the slag cleaning fumace 3 is cooled down or let to cool down, the bottom metal layer 14 in the slag cleaning fumace 3 will solidify. To melt the solidified bottom metal layer 14 is problem, because the thermal energy produced by the slag cleaning fumace 3 is normally only sufficient for keeping the material in the slag cleaning furnace 3 in molten state, not to melt it or at least not to melt it efficiently within a short period of time.

Objective of the invention

The object of the invention is to solve the above identified problem.

Short description of the invention

The method for refining copper concentrate is characterized by the definitions of independent claim 1.

Preferred embodiments of the method are defined in the dependent claims 2 to 13.

The method comprises using a suspension smelting furnace comprising a reaction shaft and a settler. The reaction shaft of the suspension smelting furnace is provided with a concentrate burner for feeding copper concentrate such as copper sulfide concentrate and/or copper matte and additionally at least reaction gas into the reaction shaft of the suspension smelting furnace to obtain a blister layer containing blister and a first slag layer containing slag on top of the blister layer in the settler of the suspension smelting furnace. The method comprises using a slag cleaning furnace. The method comprises a step for feeding copper concentrate such as copper sulfide concentrate and/or copper matte and additionally at least reaction gas into the reaction shaft of the suspension smelting furnace to obtain a blister layer containing blister and a first slag layer containing slag on top of the blister layer in the settler of the suspension smelting furnace. The method comprises additionally a step for feeding slag from the first slag layer in the settler of the suspension smelting furnace and blister from the blister layer in the settler of the suspension smelting furnace from the suspension smelting furnace into the slag cleaning furnace. The method comprises additionally a step for treating blister and slag in the slag cleaning furnace with a reduction agent to obtain a bottom metal layer containing bottom metal copper and a second slag layer containing slag on top of the bottom metal layer in the slag cleaning furnace. The method comprises additionally a step for discharging bottom metal copper from the bottom metal layer in the slag cleaning furnace. The method comprises additionally a step for discharging slag from the second slag layer in the slag cleaning furnace.

The arrangement for refining copper concentrate is characterized by the definitions of independent claim 14.

Preferred embodiments of the arrangement are defined in the dependent claims 15 to 27.

The arrangement comprises a suspension smelting furnace comprising a reaction shaft and a settler. The reaction shaft of the suspension smelting furnace is provided with a concentrate burner for feeding copper concentrate such as copper sulfide concentrate and/or copper matte and additionally at least reaction gas into the reaction shaft of the suspension smelting furnace to obtain a blister layer containing blister and a first slag layer containing slag on top of the blister layer in the settler of the suspension smelting furnace. The arrangement comprises additionally feeding means for feeding blister from the blister layer in the settler of the suspension smelting furnace into the slag cleaning furnace and for feeding slag from the first slag layer in the settler of the suspension smelting furnace into the slag cleaning furnace. The slag cleaning furnace is configured for treating blister and slag in the slag cleaning furnace with a reduction agent to obtain a bottom metal layer containing bottom metal copper and a second slag layer containing slag on top of the bottom metal layer in the slag cleaning furnace. The arrangement comprises additionally bottom metal discharging means for discharging bottom metal copper from the bottom metal layer in the slag cleaning furnace. The arrangement comprises additionally slag discharging means for discharging slag from the second slag layer in the slag cleaning furnace.

The invention is based on feeding both slag and blister from the suspension smelting furnace to the slag cleaning furnace. By feeding both slag and blister from the suspension smelting furnace to the slag cleaning furnace will a greater amount of thermal energy be fed to the slag cleaning furnace in comparison to a situation where only slag is fed from the suspension smelting furnace to the slag cleaning furnace, as in the prior art arrangement shown in figure 1. This greater amount of thermal energy can be used for melting material possible having been solidified in the slag cleaning furnace. Because both slag and blister from the suspension smelting furnace to the slag cleaning furnace, a slag storage in the settler of the suspension smelting furnace is unnecessarily. Additionally it is unnecessary to separate blister from slag in the settler, because both slag and blister are fed from the suspension smelting furnace to the slag cleaning furnace. Because of this, the settler may be made smaller, which reduces the costs for the suspension smelting furnace. If blister and slag are tapped directly into the slag cleaning furnace with very low bath level in the flash, then foaming potential will be low. The suspension smelting furnaces can be run with lower oxygen potential, as the foaming tendency will be lower. This means lower off-gas volumes and savings in operational costs in the off-gas line. Also less reducing work for the slag cleaning furnace, and therefore less energy consumption

In a preferred embodiment of the method, the method comprises feeding copper concentrate such as copper sulfide concentrate and/or copper matte and/or reaction gas into the reaction shaft of the suspension smelting furnace so that the temperature of the blister fed from the blister layer in settler of the suspension smelting furnace is between 1250 and 1400 °C.

In a preferred embodiment of the method, the method comprises preferably, but not necessarily, feeding copper concentrate such as copper sulfide concentrate and/or copper matte and/or reaction gas into the reaction shaft of the suspension smelting furnace so that the temperature of the slag fed from the first slag layer in the settler of the suspension smelting furnace is between 1250 and 1400 °C.

In a preferred embodiment of the method, the method comprises feeding copper concentrate such as copper sulfide concentrate and/or copper matte and/or reaction gas into the reaction shaft of the suspension smelting furnace so that the temperature of the blister fed from the blister layer in the settler of the suspension smelting furnace is between 1250 and 1400 °C and so that the temperature of the slag fed from the first slag layer in the settler of the suspension smelting furnace is between 1250 and 1400 °C. Sometimes there is too much heat in the suspension smelting furnace and so off gas volume becomes large. This may be even be even beneficiancy now, because operating temperature can be set higher as the melt will be laundered into the slag cleaning furnace, where high heat poses no problems. The off-gas volume can be lower than normally as suspension smelting furnaces can be run hotter, which means lower off-gas volumes

Feeding blister and/or slag having temperature between 1250 and 1400 °C from the settler of the suspension smelting furnace reduces the need for thermal energy to be fed to the slag cleaning furnace for the reduction process, because the blister and/or the slag that is fed to the suspension smelting furnace is over hot i.e. contains excess thermal energy in addition to that needed for the reaction in the suspension smelting fumace. This excess thermal energy can be used in the reduction process in the slag cleaning furnace. Especially if an electric furnace is used as a slag cleaning furnace, this is particularly advantageous, because it is less expensive to create thermal energy by a suspension smelting furnace than to create thermal energy with an electric furnace.

The method comprises preferably, but not necessarily, feeding blister from the blister layer in the settler of the suspension smelting furnace into the slag cleaning furnace without refining the blister fed from the blister layer in the settler of the suspension smelting furnace prior feeding the blister fed from the blister layer in the settler of the suspension smelting furnace into the slag cleaning furnace.

The blister feeding means for feeding blister from the blister layer in the settler of the suspension smelting furnace into the slag cleaning furnace are preferably, but not necessarily, configured for feeding blister from the blister layer in the settler of the suspension smelting furnace into the slag cleaning furnace without refining the blister fed from the blister layer in the settler of the suspension smelting furnace prior feeding the blister fed from the blister layer in the settler of the suspension smelting furnace into the slag cleaning furnace.

Another advantage achievable with the method and the arrangement according to the invention is that it makes possible a simplified layout in comparison with the prior art method and arrangement shown in figure 1. For example in the embodiments shown in figure 2, which comprises anode furnaces, material is only fed into the slag cleaning furnace from the suspension smelting furnace and material is only fed into the anode furnaces from the slag cleaning furnace.

List of figures

In the following the invention will described in more detail by referring to the figures, which

Figure 1 shows an arrangement to the prior art, Figure 2 shows a first embodiment of the arrangement,

Figure 3 shows a second embodiment of the arrangement,

Figure 4 shows a third embodiment of the arrangement, and

Figure 5 shows a fourth embodiment of the arrangement.

Detailed description of the invention

The invention relates to a method and to an arrangement for refining copper concentrate 1. First the method refining copper concentrate 1 and preferred embodiments and variants thereof will be described in greater detail.

The method comprises using a suspension smelting furnace 2 comprising a reaction shaft 5, a settler 6, and preferably, but not necessarily, an uptake 7.

The reaction shaft 5 of the suspension smelting furnace 2 is provided with a concentrate burner 8 for feeding copper concentrate 1 such as copper sulfide concentrate and/or copper matte and additionally at least reaction gas 9, and preferable also flux 10, into the reaction shaft 5 of the suspension smelting furnace 2 to obtain a blister layer 11 containing blister and a first slag layer 12 containing slag on top of the blister layer 11 in the settler 6 of the suspension smelting furnace 2.

The method comprises additionally using a slag cleaning furnace 3. The method comprises preferably using an electric furnace as the slag cleaning furnace 3.

The method comprises a step for feeding copper concentrate 1 such as copper sulfide concentrate and/or copper matte and additionally at least reaction gas 9, and preferable also flux 10, into the reaction shaft 5 of the suspension smelting furnace 2 to obtain a blister layer 11 containing blister and a first slag layer 12 containing slag on top of the blister layer 11 in the settler 6 of the suspension smelting furnace 2.

The method comprises additionally a step for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3 and for feeding blister from blister layer 11 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3.

The method comprises additionally a step for treating blister and slag in the slag cleaning furnace 3 with a reduction agent 16 such as coke to obtain a bottom metal layer 14 containing bottom metal copper and a second slag layer 15 containing slag on top of the bottom metal layer 14 in the slag cleaning furnace 3. In this step copper present in the slag fed from the first slag layer 12 in the suspension smelting furnace 2 moves from the second slag layer 15 to the bottom metal layer 14. The method comprises additionally a step for discharging bottom metal copper from the bottom metal layer 14 in the slag cleaning furnace 3.

The method comprises additionally a step for discharging slag 21 from the second slag layer 15 in the slag cleaning furnace 3. In the method slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 and blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 may be fed together from the suspension smelting furnace 2 into the slag cleaning furnace 3, as shown in figures 2 and 5. Alternatively, slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 and blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 may be fed separately from the suspension smelting furnace 2 into the slag cleaning furnace 3 as shown in figures 3 and 4.

In the method, slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 and/or blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 2 may be fed in batches into the slag cleaning furnace 3. Alternatively, slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 and/or blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 2 may be fed continuously into the slag cleaning furnace 3. By using continuous feeding, feeding means 16, 18, 23 for feeding blister from the blister layer 12 in the settler 6 of the suspension smelting furnace 2 and for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3 are easier to keep open.

The method comprises preferably, but not necessarily, a step for feeding bottom metal copper discharged from the bottom metal layer 14 in the slag cleaning furnace 3 to an anode furnace 4.

The method comprises preferably, but not necessarily, feeding copper concentrate 1 such as copper sulfide concentrate and/or copper matte and/or reaction gas 9 into the reaction shaft 5 of the suspension smelting furnace 2 so that the temperature of the blister fed from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 is between 1250 and 1400 °C.

The method comprises preferably, but not necessarily, feeding copper concentrate 1 such as copper sulfide concentrate and/or copper matte and/or reaction gas 9 into the reaction shaft 5 of the suspension smelting furnace 2 so that the temperature of the slag fed from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 is between 1250 and 1400 °C.

The method comprises preferably, but not necessarily, feeding inert gas or inert gas mixture into the slag cleaning furnace.

The method comprises preferably, but not necessarily, feeding blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3 without refining the blister fed from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 prior feeding the blister fed from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3.

The method may in some embodiments, as shown in figures 4 and 5, include using an additional slag cleaning fumace 24 in addition to the slag cleaning furnace 3. These embodiments of the method includes a step for feeding slag 21 from the slag cleaning fumace 3 into the additional slag cleaning furnace 24 and a step for treating slag 21 in the additional slag cleaning furnace 24 with a reduction agent 13 to obtain a bottom alloy layer 25 containing bottom alloy 30 and a waste slag layer 26 containing waste slag 27. These embodiments of the method includes a step for discharging bottom alloy 30 from the bottom alloy layer 25 in the additional slag cleaning furnace 24, and a step for discharging waste slag 27 from the waste slag layer 26 in the additional slag cleaning furnace 24. An electric furnace may be used as the additional slag cleaning furnace 24.

Next the arrangement for refining copper concentrate 1 and preferred embodiments and variants thereof will be described in greater detail.

The arrangement comprises a suspension smelting furnace 2 comprising a reaction shaft 5, a settler 6, and preferably, but not necessarily, an uptake 7.

The reaction shaft 5 of the suspension smelting furnace 2 is provided with a concentrate burner 8 for feeding copper concentrate 1 such as copper sulfide concentrate and/or copper matte and additionally at least reaction gas 9 and preferably also flux 11 into the reaction shaft 5 of the suspension smelting furnace 2 to obtain a blister layer 11 containing blister and a first slag layer 12 containing slag on top of the blister layer 11 in the settler 6 of the suspension smelting furnace 2.

The arrangement comprises additionally a slag cleaning furnace 3, which preferably, but not necessarily, is in the form of an electric furnace.

The arrangement comprises additionally feeding means 16, 18, 23 for feeding blister from the blister layer 12 in the settler 6 of the suspension smelting furnace 2 and for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3.

The slag cleaning furnace 3 is configured for treating blister and slag in the slag cleaning furnace 3 with a reduction agent 13 to obtain a bottom metal layer 14 containing bottom metal copper and a second slag layer 15 containing slag 21 on top of the bottom metal layer 14 in the slag cleaning furnace 3. In the slag cleaning furnace 3 copper present in the slag fed from the first slag layer 12 in the suspension smelting furnace 2 moves from the second slag layer 15 to the bottom metal layer 14.

The arrangement comprises additionally bottom metal discharging means 22 for discharging bottom metal copper from the bottom metal layer 14 in the slag cleaning furnace 3.

The arrangement comprises additionally slag discharging means 20 for discharging slag 21 from the second slag layer 15 in the slag cleaning furnace 3. The feeding means 18, 19, 23 for feeding blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 and for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 into the slag cleaning furnace 3 may, as shown in figures 3 and 4 include a separate first slag feeding means 16 for feeding separately slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 into the slag cleaning furnace 3. Such separate first slag feeding means 16 for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3 may be configured for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3 without refining the slag prior feeding the slag into the slag cleaning furnace 3.

The feeding means 18, 19, 23 for feeding blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 and for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 into the slag cleaning furnace 3 may, as shown in figures 3 and 4, include a separate blister feeding means 18 for feeding separately blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 into the slag cleaning furnace 3. Such separate blister feeding means 18 for feeding blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3 may be configured for feeding blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3 without refining the blister prior feeding the blister into the slag cleaning furnace 3.

The feeding means 18, 19, 23 for feeding blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 and for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 into the slag cleaning furnace 3 may, as shown in figures 2 and 5, include a combined slag and blister feeding means 23 for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 together with blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 into the slag cleaning furnace 3. Such combined slag and blister feeding means 23 for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 together with blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 into the slag cleaning furnace 3 may be configured for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 together with blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 3 into the slag cleaning furnace 3 without refining the slag and the blister prior feeding the slag and the blister into the slag cleaning furnace 3.

The feeding means 16, 18, 23 may be configured for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 and/or blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 2 in batches into the slag cleaning furnace 3. Alternatively, the feeding means 16, 18, 23 may be configured for feeding slag from the first slag layer 12 in the settler 6 of the suspension smelting furnace 2 and/or blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 from the suspension smelting furnace 2 continuously into the slag cleaning furnace 3.

The bottom metal discharging means 22 for discharging bottom metal copper from the bottom metal layer 14 in the slag cleaning furnace 3 is preferably, but not necessarily as shown in figures 2 to 5, connected with bottom metal feeding means 19 for feeding bottom metal copper to an anode furnace 4.

The arrangements shown in figures 2 to 5 comprises additionally anode casting molds 17 for casting copper anodes which can be used in an electrolytic refining process for further reefing of the copper.

The blister feeding means 18 for feeding blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3 are preferably, but not necessarily, configured for feeding blister from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3 without refining the blister fed from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 prior feeding the blister fed from the blister layer 11 in the settler 6 of the suspension smelting furnace 2 into the slag cleaning furnace 3.

The arrangement may comprise by gas feeding means for feeding inert gas or inert gas mixture into the slag cleaning furnace 3.

The arrangement may in some embodiments, as shown in figures 4 and 5, comprise an additional slag cleaning furnace 24 in addition to the slag cleaning furnace 3 and second slag feeding means 31 for feeding slag 21 from the slag cleaning furnace 3 into the additional slag cleaning furnace 24 to reduce the copper content in the slag and to recover copper. In such embodiments, the additional slag cleaning furnace 24 is configured for treating slag 21 in the additional slag cleaning furnace 24 with a reduction agent 13 to obtain a bottom alloy layer 25 containing bottom alloy 30 and a waste slag layer 26 containing waste slag 27. In such embodiments, the arrangement comprises additional bottom metal discharging means 28 for discharging bottom alloy 30 from the bottom alloy layer 25 in the additional slag cleaning furnace 24, and additional waste slag discharging means 29 for discharging waste slag 27 from the waste slag layer 26 in the additional slag cleaning furnace 24. The additional slag cleaning furnace 24 may be an electrical furnace.

It is apparent to a person skilled in the art that as technology advanced, the basic idea of the invention can be implemented in various ways. The invention and its embodiments are therefore not restricted to the above examples, but they may vary within the scope of the claims.