JP2022169284A - Preparation method of copper refining raw material - Google Patents

Abstract

To provide a preparation method of a copper refining raw material, capable of suppressing instability of the operation of a copper refining furnace caused by drying failure of a miscellaneous raw material in a wet state.SOLUTION: A preparation method of a copper refining raw material comprising a copper concentrate and a miscellaneous raw material in a wet state includes steps of: expanding the miscellaneous raw material in a wet state in a layering state on a surface, and scattering so as to cover from above the miscellaneous raw material in a wet state, a moisture absorbent which preferably contains copper represented by flue cinder recovered from exhaust gas of a copper refining furnace, and has a particle size smaller than that of the miscellaneous raw material in a wet state; keeping for a predetermined time a state that the miscellaneous raw material and the moisture absorbent are brought into contact with each other; and mixing the moisture absorbent with the copper concentrate while disintegrating the miscellaneous raw material whose moisture percentage is lowered due to being kept.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for preparing a copper smelting raw material comprising a copper concentrate and wet miscellaneous raw materials.

In pyrometallurgical copper smelting, the copper grade is raised to about 30% by pretreatment such as flotation, and the copper concentrate is mainly composed of chalcopyrite. This process produces high-grade blister copper with a copper grade of about 98%. Electrolytic copper is produced by electrolytically refining an anode produced by casting this blister copper. The above-mentioned smelting furnace generates high-temperature exhaust gas containing a large amount of sulfur dioxide. After the heat of this exhaust gas is recovered by a waste heat boiler, it is sent to a sulfuric acid plant as a raw material for sulfuric acid. In this sulfuric acid plant, mud-like sediment in which impurities are concentrated is generated in the process of removing the dust contained in the exhaust gas discharged from the smelting furnace and in the process of treating the waste acid produced as a by-product in the refining process. . Also in the step of purifying the electrolytic solution used in the electrorefining described above, muddy sediment in which impurities are concentrated is generated.

Since the muddy sediments generated in the above-mentioned sulfuric acid plants and electrolytic refining contain copper, these sediments are usually collected and mixed with the above-mentioned copper concentrate as miscellaneous raw materials and charged into a smelting furnace. ing. At that time, since the miscellaneous raw materials differ from the copper concentrate in properties such as composition and particle size, simply mixing them and charging them into the smelting furnace sometimes makes the operation of the smelting furnace unstable. Therefore, it is desirable to mix these miscellaneous raw materials with the copper concentrate while adjusting the properties of the mixed raw material after mixing to be substantially uniform.

For example, in Patent Document 1, as a method of mixing copper concentrate and miscellaneous raw materials so that the properties of the raw materials are almost uniform, miscellaneous raw materials are quantitatively cut out on the copper concentrate being conveyed by a belt conveyor. Techniques for adding are proposed. In addition, in Patent Document 2, although it is not intended for muddy sediments, solid particles of different types are developed on the conveyor surfaces of a plurality of belt conveyors, and the downstream side of each of these belt conveyors Techniques have been proposed to drop these solid particles from the edge of the tube toward the same location.

Japanese Patent Application Laid-Open No. 09-087760 Japanese Unexamined Patent Application Publication No. 2011-011105

In wet materials such as the above muddy sediment, as time elapses, adhering water evaporates and hardens on the surface, and the hardened surface prevents evaporation, so the inside retains a high moisture content. state. For this reason, even if the wet raw material is preheated in the drying equipment, the moisture inside cannot be sufficiently evaporated, and the wet raw material is discharged from the drying equipment in an unsatisfactory state containing residual moisture. As a result, when this preheated wet raw material is charged into a smelting furnace, the residual moisture evaporates in the smelting furnace, hindering the reaction of the copper concentrate, and the amount of evaporated water fluctuates over time. The operation of the smelting furnace becomes unstable. Furthermore, since the wet raw material generally has a bulky form with a large mass, the pneumatic conveying method of conveying the copper concentrate in the form of powder or grain using a gas flow flowing in a pipe is used. There is a risk of transportation failure occurring in the facility.

As a countermeasure for the above problem, the bucket of the shovel loader is pressed against the wet raw material to apply a load, or the wet raw material is scooped with a bucket and dropped on the floor from a height of about 4 to 5 m. Cracking the hardened shell-like part of By taking these measures, it is possible to disperse the inside of the wet raw material with a high moisture content when mixing with the copper concentrate, so it is possible to charge the raw material into the smelting furnace using air conveying equipment by gas flow. be possible. However, the above work required a lot of labor, and it took about 2 to 3 days to prepare the mixture of the copper concentrate and the wet raw material. In addition, the properties of the mixture after mixing may vary greatly due to individual differences in work. The present invention has been made in view of the above circumstances, and provides a method for preparing raw materials for copper smelting that can suppress unstable operation of a smelting furnace due to poor drying of miscellaneous raw materials in a wet state. It is intended to

The inventors of the present invention found that the surface shell-shaped portion formed by drying the wet lump of miscellaneous raw materials does not cover the entire surface of the lump, and that the composition of the miscellaneous raw materials varies and the sunshine and temperature change. It was thought that there are places where wet parts are exposed due to storage conditions such as. Therefore, from the miscellaneous raw materials in a wet state stored in a mountain-like state, the miscellaneous raw materials inside the mountain-shaped portion are extracted, mixed with a moisture absorbent and held for a while, and then mixed with copper concentrate. Then, the inventors found that the operation of these facilities can be stabilized and completed the present invention.

That is, the method for preparing a copper smelting raw material according to the present invention is a method for preparing a copper smelting raw material comprising a copper concentrate and a wet miscellaneous raw material, wherein the wet miscellaneous raw material is spread on a surface in a layered manner and , a step of spraying a moisture absorbent so as to cover it, a step of holding the miscellaneous material and the moisture absorbent in contact with each other for a predetermined time, and a miscellaneous material whose moisture content has been reduced by the holding. and mixing with the moisture absorbent and the copper concentrate while crushing.

According to the present invention, it is possible to prevent the operation of the smelting furnace from becoming unstable due to insufficient drying of miscellaneous raw materials in a wet state.

1 is a process flow diagram of a method for preparing raw materials for copper smelting according to an embodiment of the present invention. FIG. 1 is a configuration diagram of one specific example of a mixing step included in a method for preparing raw materials for copper smelting according to an embodiment of the present invention. FIG. FIG. 4 is a configuration diagram of another specific example of the mixing step included in the method for preparing raw materials for copper smelting according to the embodiment of the present invention. 1 is a configuration diagram of one specific example of a transporting step included in a method for preparing raw materials for copper smelting according to an embodiment of the present invention. FIG. 1 is a graph showing changes over time in the moisture content of miscellaneous raw materials and moisture absorbents in a wet state prepared in Examples of the present invention. 4 is a graph showing changes over time in the quality of Fe ₃ O ₄ in slag produced by charging mixed raw materials prepared in Examples and Comparative Examples of the present invention into a smelting furnace.

Hereinafter, an embodiment of the method for preparing raw materials for copper smelting according to the present invention will be described in detail. The method for preparing raw materials for copper smelting according to this embodiment of the present invention is directed to two types of granular raw materials to be processed in dry copper smelting, one of which is miscellaneous raw materials that contain water and are in a wet state. For example, a precipitate produced by adding a sulfiding agent to waste acid discharged from a sulfuric acid factory can be mentioned. The other of the two types of granular raw materials is the main raw material, copper concentrate, which is usually in a dry state. In addition, the above-mentioned miscellaneous raw materials in a wet state are not limited to the deposits generated in the sulfuric acid factory, but are copper removal slime and copper slag generated in the electrolytic refining process, the electrolytic winning process, the electrolytic solution purification process, etc. etc., may contain copper inclusions from other processes in the copper smelting plant.

The method for preparing copper smelting raw materials according to the embodiment of the present invention comprises, as shown in FIG. A contact step S2 in which a moisture absorbent is sprayed so as to cover the wet miscellaneous materials (it is not necessary to completely cover the miscellaneous materials, it is sufficient that the miscellaneous materials can be seen through the gaps), and these wet miscellaneous materials. Holding step S3 in which the hygroscopic agent is held in contact with each other for a predetermined time, and the miscellaneous raw materials whose moisture content is reduced by the holding are crushed and mixed with the above hygroscopic agent and separately prepared copper concentrate. and a conveying step S5 for conveying the mixed raw material. Each of these steps will be described in detail below.

1. Dispersion step In the dispersion step S1, wet miscellaneous raw materials that are generally piled up in a raw material storage area are placed on a flat place such as a floor surface using a shovel loader or the like, preferably with a thickness of about 2 to 10 cm. It is a step of spreading and dispersing in layers. As a result, the exposed area can be increased compared to the case of stacking in the above-described mountain shape, so that the moisture content of the miscellaneous raw materials in the wet state can be reduced, and moisture absorption can be achieved in the contact step S2, which is the next step. This allows the agent to more evenly contact the wet miscellaneous ingredients. In consideration of drainage and operation of the shovel loader, it is preferable to disperse the wet miscellaneous materials on a slightly inclined floor surface. It may also be spread and dispersed on a slightly undulating place such as on top of other raw materials or dry raw materials.

2. Contacting Step The contacting step S2 is a step of contacting the wet miscellaneous raw materials spread on a flat surface in the dispersion step S1 by spraying a moisture absorbent from above using a shovel loader or the like. At that time, the wet miscellaneous material spread in a layer may be turned upside down using a shovel loader or the like, so that the wet miscellaneous material can more uniformly come into contact with the moisture absorbent.

The hygroscopic agent used in the contact step S2 is not particularly limited as long as it is a material having a finer grain size than the miscellaneous raw material and a hygroscopicity with a lower moisture content than the miscellaneous raw material in a wet state, but it contains copper. If so, it is particularly useful because it can be used as a copper raw material in a smelting furnace. It should be noted that it is preferable to use, as an index, the above-described particle size based on a cumulative 50% particle size (D50) on a volume basis measured by a laser diffraction scattering method. Examples of the hygroscopic agent include copper powder such as copper slag powder, and flue dust collected by a waste heat boiler, an electric dust collector, or the like into which exhaust gas discharged from a flash furnace or a converter is introduced.

The amount of the moisture absorbent to be sprayed is preferably about 30 to 300 parts by weight on a dry matter basis with respect to 100 parts by weight on a dry matter basis of the miscellaneous raw materials in a wet state. If the amount to be applied is less than 30 parts by mass, it is difficult to obtain the effect of moisture absorption. Conversely, even if the amount to be applied exceeds 300 parts by mass, no further effect of moisture absorption can be obtained, which is disadvantageous in terms of cost. .

3. Holding Step The holding step S3 is a step for reducing the moisture percentage contained in the wet miscellaneous raw material by keeping the moisture absorbent and the wet miscellaneous raw material in contact with each other for a predetermined time. In this holding step S3, if necessary, air may be blown toward the wet miscellaneous materials, or the wet miscellaneous materials may be stirred using a shovel loader or the like.

The holding time of this holding step S3 is not particularly limited, but the moisture content of miscellaneous raw materials in a wet state, which is the target of the preparation method of the embodiment of the present invention, tends to decrease as the holding time of the holding step S3 increases. , and the moisture content drops significantly even after about 8 hours from the start. However, if the elapsed time from the start exceeds about 24 hours, the rate of decrease in moisture content becomes extremely slow, so that the predetermined holding time is appropriately about 8 to 24 hours.

It is considered that the decrease in the moisture content of the wet miscellaneous material due to the hygroscopic agent is mainly caused by the movement of water due to the capillary phenomenon that occurs at the contact portion between the wet miscellaneous material and the hygroscopic agent. Fumes produced in copper smelting furnaces usually contain copper sulfide scattered from the copper smelting furnace and copper sulfate that is burned by the copper sulfide. is doing. Since the anhydrous copper sulfate in the flue dust undergoes a hydration reaction with adhering water contained in the wet miscellaneous raw materials and generates heat, it can be expected to accelerate the evaporation of the adhering water. Furthermore, since copper sulfate anhydrate takes in the adhering water as water of crystallization to form copper sulfate pentahydrate, it can be expected that the water content of miscellaneous raw materials in a wet state will decrease.

4. Mixing Step The mixing step S4 is a step of crushing the miscellaneous raw materials whose moisture content has decreased in the holding step S3 and mixing them with a moisture absorbent and separately prepared copper concentrate. During this mixing, the mixing ratio of the miscellaneous raw material containing the moisture absorbent and the copper concentrate is usually 1 to 15 parts by mass of the miscellaneous raw material on a dry matter basis with respect to 100 parts by mass of the copper concentrate on a dry matter basis. is preferred. The mixing method in this mixing step S4 is not particularly limited. For example, mixing may be performed by stirring using a shovel loader or the like, or mixing may be performed using a general powder mixer.

Alternatively, as shown in FIG. 2, from a copper concentrate hopper 2 provided above the upstream end of one or more belt conveyors 1, copper concentrate is fed through a first quantitative cutting device 3 such as a rotary feeder. A certain amount of ore is cut out and spread on the conveyor surface of the belt conveyor 1, and a secondary raw material hopper 4 provided downstream of the copper concentrate hopper 2 in the conveying direction of the conveyor 1 is fed to a second quantitative cutting such as a rotary feeder. A fixed amount of miscellaneous raw materials may be cut out through the dispensing device 5 and mixed by spreading on the copper concentrate on the conveyor surface. In the case of FIG. 2, the mixing hopper 6 can receive the mixed raw material in which the mixing ratio of the copper concentrate and the miscellaneous raw material is adjusted by controlling the amount of raw material discharged from both hoppers 2 and 4 . In addition, since the degree of mixing increases as the number of belt conveyors 1 provided in series increases, the number of belt conveyors 1 is preferably about 2 to 4.

In addition, as shown in FIG. 3, a copper concentrate is fed from a copper concentrate hopper 12 provided above the upstream end of the first belt conveyor 11A through a first quantitative cutting device 13 such as a rotary feeder. It is cut out by quantity and spread on the conveyor surface of the first belt conveyor 11A, and a second fixed quantity cutting device 15 such as a rotary feeder is fed from a miscellaneous raw material hopper 14 provided above the upstream end of the second belt conveyor 11B. A certain amount of miscellaneous raw materials are cut out through the feeder and spread on the conveyor surface of the second belt conveyor 11B, and the same copper concentrate and miscellaneous raw materials are respectively supplied from the downstream ends of both the first and second belt conveyors 11A and 11B. Mixing may be performed by dropping into the mixing hopper 16 . At that time, at least one of the first fixed-quantity cutting device 13 and the second fixed-quantity cutting device 15 may be operated intermittently, or these may be operated alternately. In the case of FIG. 3, the mixing ratio of the copper concentrate and miscellaneous raw materials is adjusted by controlling the amounts of the hoppers 12 and 14 and the traveling speed of the belt conveyors 11A and 11B. Mixed ingredients may be received in mixing hopper 16 .

2 and 3, the drop when the miscellaneous raw materials are dropped onto the conveyor surface of the belt conveyor, and the drop when the mixed raw materials are dropped from the downstream end of the belt conveyor. It is preferable to secure a drop of 50 cm or more. As a result, lumps of miscellaneous raw materials can be loosened and charged into a drying facility or a smelting furnace. In addition, since the cohesive force between the particles of the miscellaneous raw materials that have undergone the dehydration step S3 is reduced, the lumped miscellaneous raw materials can be easily crushed even when mixed by any of the above methods. Since the miscellaneous raw material has a low moisture content and is less sticky, it can be easily mixed with the copper concentrate.

5. Conveying Step The conveying step S5 is a step of conveying the mixed raw material obtained in the above-described mixing step S4 to a smelting furnace or a preceding drying facility. This drying equipment preheats and dries the mixed raw material before charging it into the smelting furnace. Steam dryers may be mentioned. This dryer dries the material to be dried, which is loaded from one end thereof, through a steam pipe while being stirred by the rotation of the cylindrical body and moved in the direction of the central axis.

There are no particular restrictions on the method of conveying the mixed raw material, and general mechanical conveying methods such as belt conveyors and bucket conveyors may be used. preferable. The pneumatic conveying method can be broadly classified into low-concentration conveying, in which granular material is conveyed in a dispersed state by high-speed air, and high-concentration conveying, in which granular material is conveyed in a plug shape by low-speed air current. Among these, in the case of raw materials for copper smelting, high-concentration transportation is preferable because wear of the transportation pipe can be suppressed and the mixed raw materials can be conveyed with a relatively small amount of air consumption without separation.

FIG. 4 shows a general configuration diagram of the above-described high-density transportation. The pneumatic conveying equipment shown in FIG. Compressed air for conveying air is introduced into the supply source tank 20 .

As described above, by adopting the method for preparing raw materials for copper smelting according to the embodiment of the present invention, it is possible to reduce the moisture content in the inside of the miscellaneous raw materials in a wet state. can prevent instability. In addition, by reducing the moisture content of miscellaneous raw materials in a wet state, the cohesive force between particles can be reduced and the state can be easily crushed. By applying a physical force such as friction with the fiber, the fiber is appropriately loosened, and thus the drying efficiency in the drying equipment can be improved. Furthermore, since the miscellaneous raw material pulverized after the moisture content is reduced contains almost no agglomerated aggregates of particles, even if pneumatic conveying is employed, conveyance failures are less likely to occur.

(Example)
Precipitates generated by adding a sulfiding agent to the waste acid produced as a by-product in the refining process at a sulfuric acid manufacturing plant are prepared as wet miscellaneous raw materials, mixed with copper concentrates, and charged into drying equipment. did. Before mixing with the copper concentrate, the wet miscellaneous raw material is spread on a floor surface in a layer of about 2 cm thick, and a copper-containing powder having the same mass as the miscellaneous raw material on a dry matter basis as a moisture absorbent is spread thereon. (copper slag powder) was evenly dispersed using a shovel loader. After spraying the hygroscopic agent, the moisture content of the miscellaneous raw materials in the wet state was lowered by keeping the state as it was for 24 hours.

The moisture content of the miscellaneous raw material in a wet state before spreading on the floor surface and the moisture content of the miscellaneous raw material after 24 hours after spreading on the floor surface were each dried at an ambient temperature of 105 ° C. for 30 minutes. As shown in FIG. 5, the moisture content decreased from 23.8% by mass to 8.6% by mass by keeping the powder in contact with the copper-containing powder for 24 hours. On the other hand, the copper-containing powder increased from 3.5% by mass to 5.2% by mass. In addition, it is considered that the portion of the decreased moisture content that was not incorporated into the copper-containing powder evaporated or dripped.

After the 24-hour holding was completed, the miscellaneous raw materials were scooped out together with the copper-containing powder with a bucket of a shovel loader and dropped from a height of about 50 cm onto the floor. At that time, when comparing the size of the lump of miscellaneous raw materials before dropping and the size of the lump of miscellaneous raw materials after dropping, the lump after dropping is on average 1/4 to 8 times smaller than the lump before dropping. It was finely pulverized to about 1.

The miscellaneous raw materials and the copper-containing powder dropped in this way were scooped up and put into a powder mixer, and then the copper concentrate was put in and mixed. At that time, the miscellaneous raw material was mixed at a mixing ratio of 5 parts by mass (dry matter basis) to 100 parts by mass (dry matter basis) of the copper concentrate. A part of the obtained mixed raw material was charged into a drying furnace via a belt conveyor, and then charged from the drying furnace to a smelting furnace via a chain conveyor and a pneumatic carrier. As a result, the drying furnace and the smelting furnace could be stably operated without any particular problems.

(Comparative example 1)
The same amount of wet miscellaneous materials and copper-containing powder as in the example was prepared, but without spreading them on the floor or holding them for 24 hours, they were simply placed in a bucket of a shovel loader to a height of about 50 cm. dropped to the floor. As a result, the size of the lumps of miscellaneous materials before dropping was almost the same as the size of the lumps after dropping. After that, when it was tried to mix with copper concentrate and charge it into the smelting furnace via the drying furnace in the same way as in the example, the equipment protection stop occurred due to the increase in the current value in the chain conveyor, and the air current conveyer Obstruction by nodules occurred at .

(Comparative example 2)
A copper smelting raw material was prepared in the same manner as in Comparative Example 1 above except that the wet miscellaneous raw materials and copper-containing powder were dropped from a height of 4 to 5 m instead of a height of 50 cm. As a result, the size of the lumps of miscellaneous raw materials was reduced to about half after the drop compared to before the drop, but many of them were about the same size as before the drop. It was

(Comparative Example 3)
The same conditions as in Comparative Example 2 above were repeated until the size of the miscellaneous material obtained when the miscellaneous material was dropped from a height of about 50 cm in the example was approximately the same as that of the miscellaneous material. dropped the powder. Thereafter, it was mixed with copper concentrate and charged into a smelting furnace via a drying furnace in the same manner as in the Examples. Then, the slag produced from the smelting furnace was sampled three times at the start of treatment in the smelting furnace, 8 hours after the start of treatment, and 16 hours after the start of treatment, and their triiron tetroxide (Fe ₃ O ₄ ) The quality was analyzed. The reason for analyzing the Fe ₃ O ₄ quality in this way is that if the operation of the smelting furnace becomes unstable _, the progress of the reaction will vary and the Fe ₃ O ₄ quality of the slag will increase _. This is because the stability of operation can be evaluated by using as an index.

The analysis results are shown in FIG. 6 together with the results of the same analysis as in the above example. In addition, in FIG. 6, the Fe ₃ O ₄ quality before the start of treatment was set to 1.0. As can be seen from the results of FIG. 6, in Comparative Example 3, the Fe ₃ O ₄ quality in the slag extracted from the smelting furnace after 8 hours and 16 hours from the start of treatment was about 1.04 times the reference value. Although it increased, it decreased to about 0.95 times after 16 hours from the start of treatment in the example. Therefore, it can be seen that the operation of the smelting furnace in Example is more stable than in Comparative Example 3. Here, the standard value is the value obtained by analyzing the slag sampled when the operation is in a steady state when only the dry copper concentrate, which does not contain wet miscellaneous raw materials, is charged into the smelting furnace as a raw material. is.

1 Belt Conveyor 2, 12 Copper Concentrate Hopper 3, 13 First Quantitative Extraction Device 4, 14 Miscellaneous Material Hopper 5, 15 Second Quantitative Extraction Device 6, 16 Mixing Hopper 11A First Belt Conveyor 11B Second Belt Conveyor 20 Source tank 21 Transport pipe 22 Destination tank

Claims (3)

A method for preparing a copper smelting raw material comprising a copper concentrate and a wet miscellaneous raw material, comprising a step of spreading the wet miscellaneous raw material on a surface in a layered manner and spraying a moisture absorbent so as to cover it from above. a step of holding the miscellaneous raw materials and the hygroscopic agent in contact with each other for a predetermined period of time; A method for preparing raw materials for copper smelting, characterized by comprising the steps of: 2. The method for preparing raw materials for copper smelting according to claim 1, wherein said desiccant contains copper and has a particle size smaller than that of said miscellaneous raw materials in a wet state. 3. The method for preparing raw materials for copper smelting according to claim 1 or 2, wherein said desiccant is flue ash recovered from exhaust gas of a copper smelting furnace.

Images