JP2008062169A - Method and system for treating fine powder containing calcium component and lead component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating fine powder by which a calcium component and a lead component can be separated and recovered from fine powder containing the calcium component and the lead component by a simple operation while reducing the number of treatment steps and chemicals to be used. <P>SOLUTION: The method for treating fine powder comprises: a step (A) of mixing fine powder containing the calcium component and the lead component, water and a sulfurizing agent to obtain slurry containing sulfurized lead being solid content; a step (B) of adding sulfuric acid to the slurry obtained in the step (A) to adjust the pH of the slurry to 1.5-7.5 and obtain the slurry containing sulfurized lead being the solid content and calcium sulfate; a step (C) of adding a collecting agent to the slurry obtained in the step (B) to hydrophobize the sulfurized lead in the slurry; and a step (D) of subjecting the slurry obtained in the step (C) to flotation treatment to obtain a floating mineral containing the sulfurized lead and a precipitated mineral containing calcium sulfate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for treating fine powder containing calcium components and lead components such as fine powder obtained by a chlorine bypass technique for extracting a part of exhaust gas from a cement kiln, and more specifically, containing calcium components and lead components. The present invention relates to a processing method for separating and collecting calcium components and lead components contained in fine powder.

  In cement kilns that use waste such as household waste and incinerated ash as part of the raw material, exhaust gas with a high chlorine content is generated. This exhaust gas is treated by chlorine bypass technology. Chlorine bypass technology is to extract part of the exhaust gas from the cement kiln, and then collect coarse powder (solid content with low chlorine content) in the extracted high-temperature exhaust gas with a cyclone and use it as a cement raw material in the cement kiln. On the other hand, the fine powder (solid content with a large chlorine content) generated by cooling the exhaust gas that has passed through the cyclone is collected by a dust collector such as a bag filter to remove the chlorine component. The collected fine powder contains a calcium component, a potassium component, a lead component, a chlorine component, and the like. In addition, this fine powder can be returned to a cement kiln as a cement raw material which has a calcium component as a main component, if a potassium component, a lead component, a chlorine component, etc. are removed.

On the other hand, a technique is known in which flotation is performed on dust containing a heavy metal component such as a chlorine component, a calcium component, and a lead component to separate and recover the calcium component and the heavy metal component such as a lead component.
For example, a method for treating fly ash generated when incineration waste, a washing step of washing fly ash using water while blowing carbon dioxide gas, and a solid residue obtained in the washing step On the other hand, the flotation using a flotation agent for calcium carbonate is carried out, and the first flotation process for recovering calcium carbonate as floss (flotation), and the settling residue (precipitation) in the first flotation process to sulfuric acid To form a metal salt of heavy metal, and further add water to dissolve the metal salt. At the same time, the dissolved copper ions are precipitated as metal copper to form a mixture containing the metal copper, lead sulfate, etc. Thereafter, the mixture is recovered as a filter cake by filtration or the like, and the filter cake recovered in the leaching process is floated by using an activating agent such as a sulfiding agent, a collector and a foaming agent. Mineral processing, metal copper and sulfur as floss Processing method of fly ash and a second flotation step of recovering the lead, has been proposed (Patent Document 1).
JP-A-8-323321

The fine powder obtained by the chlorine bypass technique described above contains a calcium component, a potassium component, a lead component, a chlorine component, and the like. Among these, a potassium component, a chlorine component, etc. can be collect | recovered as a component in the filtrate after a water-washing process.
However, when trying to separate and recover the calcium component that can be used as a cement raw material and the lead component that can be used as a non-ferrous refining raw material, for example, using the technique described in the above-mentioned literature, the number of processes and chemicals is large. Therefore, a great deal of labor is required and the cost is increased.
Therefore, the present invention provides a treatment method that can separate and recover the calcium component and the lead component from the fine powder containing the calcium component and the lead component by a simple operation with a small number of steps and chemicals. For the purpose.

  As a result of intensive studies to solve the above problems, the present inventor mixed a fine powder containing a calcium component and a lead component, water, and a sulfiding agent to obtain a slurry containing lead sulfide that is a solid component. Then, sulfuric acid is added to the slurry to adjust the pH of the slurry to 1.5 to 7.5, to further produce calcium sulfate as a solid content, and then to the obtained lead sulfide and calcium sulfate. To the slurry containing, the collection agent is added to perform the hydrophobization treatment, and when the slurry is low in foaming, the foaming agent is added, and then the flotation using a flotation machine is performed. It has been found that calcium sulfate can be contained mainly in the sedimentation and lead sulfide can be contained mainly in the floatation, and the calcium component and the lead component can be separated and recovered easily. Was completed.

That is, the present invention provides the following [1] to [2].
[1] (A) A lead sulfide production step of obtaining a slurry containing lead sulfide, which is a solid component, by mixing fine powder containing a calcium component and a lead component, water, and a sulfurizing agent, and (B) Sulfuric acid is added to the slurry obtained in the step (A) to adjust the pH of the slurry to 1.5 to 7.5 to obtain a slurry containing lead sulfide and calcium sulfate as solid components. Obtained in the step (C), a lead sulfide hydrophobizing step in which a collector is added to the slurry obtained in the step (C) and the slurry obtained in the step (B) to hydrophobize the lead sulfide in the slurry. A fine powder containing a calcium component and a lead component, including a floatation containing lead sulfide and a lead / calcium separation step for obtaining a precipitate containing calcium sulfate by subjecting the resulting slurry to a flotation process Processing method.
[2] A lead sulfide generator for obtaining a slurry containing lead sulfide, which is a solid component, by mixing fine powder containing a calcium component and a lead component, water, and a sulfiding agent, and the lead sulfide The sulfuric acid is added to the slurry obtained by the production device, and the calcium sulfate production device for obtaining a slurry containing lead sulfide and calcium sulfate, which are solid components, and the slurry obtained by the calcium sulfate production device are collected. A lead sulfide hydrophobizing device for hydrophobizing lead sulfide in the slurry by adding an agent and a flotation device for subjecting the slurry obtained by the lead sulfide hydrophobizing device to a flotation process The processing system of the fine powder containing the calcium component and the lead component characterized by the above-mentioned.

According to the treatment method of the present invention, the distribution ratio of the lead component is large and the distribution ratio of the calcium component is small from the fine powder containing the calcium component and the lead component by a simple operation with a small number of steps and chemicals. It can be divided into floatation (floth) and sedimentation with a high calcium component distribution rate and a low lead component distribution rate.
Among these, a calcium component is collect | recovered as calcium sulfate and can be used as a cement raw material.
The lead component is recovered as lead sulfide and can be used as a non-ferrous smelting raw material by Yamamoto reduction. In particular, as a solid content recovered by flotation, even if a substance other than calcium sulfate and lead sulfide (for example, a compound such as silicon and aluminum) is contained at a high content, the other substance However, since it is recovered as a precipitate with calcium sulfate, the content of lead sulfide contained in the float can be kept high, and a high-quality non-ferrous refining raw material can always be obtained.

Moreover, since the sulfuric acid is added after adding the sulfurizing agent, the processing method of this invention has the following advantages compared with the case where a sulfurizing agent is added after adding a sulfuric acid.
First, the recovery rate of lead from fine powder containing a calcium component and a lead component can be increased.
Second, the recovery rate of lead from the fine powder can be stabilized regardless of the magnitude of the CaO content in the fine powder containing the calcium component and the lead component and the amount of sulfuric acid added. it can. In this respect, when adding a sulfiding agent after adding sulfuric acid, the numerical range of the optimum amount of sulfuric acid differs depending on the CaO content in the fine powder. There is a problem that the recovery rate decreases.
Third, even if the time from pH adjustment by addition of sulfuric acid to the start of flotation is long, the lead recovery rate does not decrease. In this regard, when adding a sulfurizing agent after adding sulfuric acid, the pH tends to increase with the passage of time after adjusting the pH by adding sulfuric acid, and the time from the time of pH adjustment to the start of flotation is considered. If long, the pH may exceed the upper limit of the numerical range suitable for flotation.

Hereinafter, the processing method of the fine powder containing the calcium component and lead component of this invention is demonstrated, referring drawings.
FIG. 1 is a flow chart showing an example of a method for treating fine powders containing a calcium component and a lead component of the present invention. FIG. 2 is a flowchart showing a method (a method of a comparative example) in which the order of the lead sulfide generation step and the calcium sulfate generation step is reversed in the treatment method of the present invention.
As shown in FIG. 1, the processing method of the fine powder containing the calcium component and the lead component of the present invention comprises: (A) a fine powder that is a processing object, water, and a sulfiding agent; (Sulfuric acid producing step), (B) sulfuric acid is added to the slurry obtained in step (A) to adjust the pH to 1.5 to 7.5, and lead sulfide and sulfuric acid are obtained. A step of obtaining a slurry containing calcium (calcium sulfate generation step), and a step of adding a collection agent to the slurry obtained in step (B) to hydrophobize lead sulfide in the slurry (lead) (Sulfide hydrophobization step) and (D) the slurry obtained in step (C) is subjected to a flotation process to separate lead sulfide and calcium sulfate (lead / calcium separation step). Hereinafter, each step will be described.

[(A) Lead sulfide production process]
This step is a step of obtaining a slurry containing lead sulfide that is a solid component by mixing fine powder containing a calcium component and a lead component, water, and a sulfurizing agent.
As an example of the fine powder to be treated in the present invention, the fine powder collected in the course of the treatment of the exhaust gas of the cement kiln by the chlorine bypass technique, incineration fly ash, molten Examples include fly ash.
Although the content rate (mass ratio of CaO conversion) in the fine powder used as the process target of this invention is not specifically limited, Preferably it is 5-70 mass%, More preferably, it is 10-60 mass%, Most preferably It is 15-50 mass%. When the content is less than 5% by mass, the amount of the calcium component obtained by the treatment method of the present invention is small, and it is not possible to sufficiently recycle the calcium component. When this content rate exceeds 70 mass%, the recovery rate of lead in the step (D) may decrease.
Although the content rate (mass ratio of PbO conversion) of the lead component in the fine powder which is the processing target of the present invention is not particularly limited, it is preferably 0.1 to 10% by mass, more preferably 0.5 to 9% by mass. %, Particularly preferably 1 to 8% by mass. When the content is less than 0.1% by mass, the content of lead is too small, and the necessity of applying the method of the present invention is reduced. If the content exceeds 10% by mass, a large amount of lead may remain in the calcium sulfate separated and recovered in step (D).

As a method of mixing the fine powder containing the calcium component and the lead component, water, and the sulfiding agent, for example, in a liquid tank with a stirring blade, water, a fine powder containing the calcium component and the lead component, A method of containing a sulfiding agent and stirring to obtain a substantially uniform slurry can be mentioned.
The amount of the fine powder containing a calcium component and a lead component per liter of water is preferably 5 to 300 g, more preferably 20 to 250 g, and particularly preferably 50 to 200 g. If the amount is less than 5 g, the amount of water per unit mass of the fine powder containing the calcium component and the lead component increases, and the efficiency of the treatment decreases. When the amount exceeds 300 g, the separation performance of the lead component and the calcium component in the lead / calcium separation step (D) decreases.

Examples of the sulfiding agent include sodium hydrosulfide (NaSH), sodium sulfide (Na ₂ S), hydrogen sulfide gas (H ₂ S), and the like.
Examples of the lead sulfide generated in the slurry obtained in this step include lead sulfide (PbS).
The addition amount of the sulfiding agent is determined according to the amount of the lead component in the fine powder before slurrying. Specifically, it is desirable to add a sulfurizing agent in an amount such that the molar ratio of S (sulfur in sulfurizing agent) / Pb (lead in fine powder) is in the range of 0.8 to 3.0. However, the addition amount of the sulfurizing agent is not particularly limited within a narrow numerical range because the optimum value varies depending on other metal components contained in the fine powder.
In the present invention, the pH can be adjusted within an appropriate numerical range by adding sulfuric acid in the step (B) even when the pH is excessively increased by adding an excessive sulfurizing agent. . In this regard, when a sulfurizing agent is added after the addition of sulfuric acid (when the order of step (A) and step (B) is reversed; in the case of the comparative example shown in FIG. 2), the sulfurating agent is added excessively. The pH value in flotation may exceed the upper limit of the proper numerical range.
In this step, it is preferable to sufficiently stir after adding the sulfurizing agent. The stirring time is preferably 5 to 30 minutes.

[(B) Calcium sulfate production step]
In this step, sulfuric acid is added to the slurry obtained in step (A), and the pH of the slurry is 1.5 to 7.5, preferably 2.0 to 7.0, particularly preferably 2.5 to. This is a step of adjusting to 6.5 and obtaining a slurry containing lead sulfide and calcium sulfate as solid components. If the pH is less than 1.5 or exceeds 7.5, the lead recovery rate in step (D) decreases.
As embodiment of this process, following (B-1) and (B-2) are mentioned, for example.
(B-1) Method using pH measurement means This method is preferably carried out using the pH measurement means (pH meter) while adding sulfuric acid to the slurry obtained in step (A), preferably with stirring. By measuring the pH of the slurry, the pH is adjusted to 1.5 to 7.5, preferably 2.0 to 7.0, particularly preferably 2.5 to 6.5 (see FIG. 4). .
According to this method, the pH can be adjusted only by using the pH measuring means.
The pH in this method may be adjusted by measuring the pH of the slurry in step (C) (lead sulfide hydrophobizing step) instead of measuring the pH of the slurry in step (B). This is because the slurry in the step (B) and the slurry in the step (C) may be regarded as having the same pH.
(B-2) Method for Predetermining the Amount of Addition of Sulfuric Acid In this method, before the step (A), the content of CaO in the fine powder that is the object of treatment of the present invention is measured, and the step (B) In the above, based on the measured value of the content of CaO, the molar ratio of H ₂ SO ₄ / CaO in the slurry is 0.85 to 1.20, preferably 0.90 to 1.12, more preferably 0. This is a method of adding an amount of sulfuric acid in the range of .92 to 1.05 (see FIG. 5).
According to this method, the pH of the slurry can be in the range of 1.5 to 7.5 without measuring the pH value by the pH measuring means.

[(C) Lead sulfide hydrophobization process]
This step is a step of hydrophobizing the lead sulfide in the slurry by adding a collector to the slurry obtained in step (B).
In this step, lead sulfide is hydrophobized as a pretreatment for flotation in step (D) (lead / calcium separation step).
In the flotation, air is supplied to water containing particles having a hydrophobic surface and particles having a hydrophilic surface, and particles having a hydrophobic surface are attached to the surface of the bubbles of the air. The bubbles to which the particles are attached are separated into particles having a hydrophilic surface that is a sedimentation and particles having a hydrophobic surface that is a floatation by levitation in water by buoyancy.
The collector used in the present invention is for increasing the hydrophobicity of the lead sulfide produced in the step (A). After the lead sulfide is made hydrophobic by the collector, it adheres to the surface of the foam and floats in the water to become a float.

Examples of the collector include xanthate, acidic dithiophosphates (trade name: Elofloat), alkyl sulfates such as sodium n-dodecyl sulfate, unsaturated aliphatic carboxylates such as sodium oleate, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together.
Of these, xanthate, acidic dithiophosphates, sodium oleate and the like are preferably used in the present invention.
Here, the xanthates, -OC (= S) -S ^- refers to xanthate having the chemical structure. Examples of xanthate include R—OC (═S) —S ^— M ⁺ (wherein R is an alkyl group having 1 to 20 carbon atoms (preferably 2 to 5), M is an alkali metal such as Na or K, or A compound represented by the general formula of NH _{4 and the} like).
The amount of the collection agent added is preferably 10 mg or more, more preferably 30 mg or more, and particularly preferably 50 mg or more with respect to 1 liter of the slurry. If the amount is less than 10 mg, it becomes difficult to sufficiently float the lead sulfide as a float.
The upper limit of the added amount of the collecting agent is not particularly limited, but is preferably 1,000 mg or less, more preferably 500 mg or less, with respect to 1 liter of slurry from the viewpoint of reduction of drug cost.

In this step, a foaming agent can be added to the slurry. By using a foaming agent, it is possible to promote floating of the ore in the flotation. The foaming agent is usually added after hydrophobizing lead sulfide.
Examples of the foaming agent include methyl isobutyl carbinol (MIBC; 4-methyl-2-pentanol), methyl isobutyl ketone, pine oil, ethylene glycol, propylene glycol methyl ether, cresolic acid and the like. As the foaming agent, in addition to the above-mentioned examples, for example, a chain hydrocarbon group having 6 to 8 carbon atoms (such as an alkyl group) or a cyclic hydrocarbon group having 10 to 15 carbon atoms (aromatic group, cyclohexane) A compound having a hydrophobic group such as an alkyl group or the like and a hydrophilic group such as a hydroxyl group or a carboxyl group can also be used.
The amount of the foaming agent added is preferably 5 to 100 mg with respect to 1 liter of the slurry. In addition, in this invention, addition of a foaming agent is not essential and is arbitrary.

[(D) Lead / calcium separation process]
This step is a step of subjecting the slurry obtained in the step (C) to a flotation process to obtain a float containing lead sulfide and a deposit containing calcium sulfate.
Flotation means include Fahrenwald type flotation machine (FW type flotation machine), MS type flotation machine, Feger Glen type flotation machine, Agiteya type flotation machine, Worman type flotation machine, etc. Machine.
Flotation can be separated from other components of the slurry (liquid content, sedimentation) by recovering the solid content present in the upper region (particularly near the liquid surface) of the slurry liquid.
Floats contain a calcium component and a lead component because the distribution ratio of lead (Pb) (in other words, the mass proportion of Pb in the flotation in the total amount of Pb in the flotation and Pb in the subsidence) is large. Can be separated and recovered as a lead-containing substance derived from fine powder.
The distribution ratio of lead to the float ore varies depending on the content of the calcium component contained in the fine powder that is the object to be treated of the present invention, but is usually 60% by mass or more.
The content (mass%) of lead in the float is varied depending on the magnitude of the content of the calcium component contained in the fine powder that is the object to be treated of the present invention, but is usually 10 mass% or more. .
The sedimentation can be separated from the other components of the slurry (liquid content, floatation) by recovering the solids present in the lower region (especially on the bottom surface) of the slurry liquid.
Contrary to floatation, sedimentation has a high calcium sulfate distribution ratio and a low lead sulfide distribution ratio, and therefore can be used as a cement raw material. The sedimentation may contain compounds such as silicon and aluminum.
The distribution ratio of calcium (Ca) to the ore is usually 80% by mass or more.

Next, the fine powder processing apparatus of the present invention will be described. FIG. 3 is a diagram conceptually showing an example of the fine powder processing system of the present invention.
In FIG. 3, the processing system for fine powder according to the present invention includes a mixing tank 1 for storing a slurry in which a fine powder containing a calcium component and a lead component, which are processing objects, and water are mixed, and a mixing tank 1. A lead sulfide generation tank 2 for adding lead sulfide to the supplied slurry to generate lead sulfide, a sulfide storage tank 3 for supplying sulfide agent to the lead sulfide generation tank 2, and lead sulfide A sulfuric acid is added to the slurry supplied from the product generation tank 2 to produce calcium sulfate, a sulfuric acid production tank 4 for supplying the sulfuric acid to the calcium sulfate production tank 4, and a calcium sulfate production A trapping agent is added to the slurry supplied from the tank 4 to increase the hydrophobicity of the lead sulfide in the slurry, and a trap for supplying the trapping agent to the hydrophobic reaction tank 6. The storage tank 7 and the storage tank 6 in the hydrophobization reactor 6 PH measuring means (pH meter) 10 for measuring pH of Lee, flotation machine 9 for performing flotation on the slurry supplied from the hydrophobization reaction tank 6, and flotation from the hydrophobization reaction tank 6 A foaming agent storage tank 8 is provided for supplying the foaming agent at a predetermined point in the flow path to the selector 9.

The pH measurement means 10 may be installed anywhere from the calcium sulfate production tank 4 to the hydrophobization reaction tank 6 (process (B) to process (C)), but is preferably installed in the hydrophobization reaction tank 6. When the installation location of the pH measuring means 10 is, for example, the calcium sulfate production tank 4 or the flow path between the calcium sulfate production tank 4 and the hydrophobization reaction tank 6, the inclusion of CaO in the fine powder to be treated This is because the fluctuation of the measured value of the pH of the slurry may become large before reaching the hydrophobization reaction tank 6 depending on the magnitude of the rate and the solid-liquid ratio of the slurry.
Between each part (except for the pH measuring means 10) constituting the processing system of the present invention, a slurry flow path or a supply path for a chemical such as a sulfurizing agent is provided.
In the treatment system of the present invention, a portion including the lead sulfide generation tank 2 and the sulfiding agent storage tank 3 constitutes a lead sulfide generation apparatus. The part including the calcium sulfate production tank 4 and the sulfuric acid storage tank 5 constitutes a calcium sulfate production apparatus. The part including the hydrophobization reaction tank 6, the collection agent storage tank 7, and the foaming agent storage tank 8 constitutes a lead sulfide hydrophobization apparatus. The flotation machine 9 is a flotation apparatus.
When the content of CaO in the fine powder that is the object to be treated is measured in advance and the supply amount of sulfuric acid from the sulfuric acid storage tank 6 is determined, the pH measuring means 10 can be omitted.
In the present invention, either a continuous processing method or a batch processing method and a processing system may be adopted, but from the viewpoint of processing efficiency, a continuous processing method and a processing system are preferable.

The present invention will be described with reference to examples and comparative examples. The following “%” is based on mass unless otherwise specified.
[Preparation of fine powder containing calcium and lead components]
Four types (A to D) shown in Table 1 were prepared as fine powders containing a calcium component and a lead component as treatment objects. All of these fine powders are fine powders collected in the process of exhaust gas treatment of cement kiln by chlorine bypass technology.

[Example 1]
Using the continuous processing system shown in FIG. 3, the fine powder A was processed as follows.
Water and fine powder A in an amount of 150 g per liter of water were put into the mixing tank 1 equipped with a stirring blade and stirred to obtain a uniform slurry.
After introducing this slurry into a lead sulfide production tank 2 (capacity: 90 liters) equipped with a stirring blade, the amount of sodium hydrosulfide added at 3,000 mg (solid content) per liter of slurry to the slurry in the tank Then, a sodium hydrosulfide aqueous solution (concentration: 20% by mass) was added and stirred under a residence time of 30 minutes to generate lead sulfide (including lead sulfide).
Next, the slurry was introduced into a calcium sulfate production tank 4 (capacity: 45 liters) equipped with a stirring blade, and then the pH of the slurry with respect to the slurry in the tank (however, the measurement location was the hydrophobization reaction tank 6). ) Was added in the amount of sulfuric acid (concentration: 98% by mass) having the value shown in FIG. 4, and stirred for a residence time of 30 minutes to generate calcium sulfate. The amount of sulfuric acid added was set to five variables as shown in FIG. Experiments were performed for each of these five variables.

Next, after introducing this slurry into a hydrophobizing reaction tank 6 (capacity: 45 liters) with a stirring blade, slurry 1 was used as a collection agent for increasing the hydrophobicity of lead sulfide with respect to the slurry in the tank. An amyl xanthate aqueous solution (concentration: 0.4 mass%, chemical formula of amyl xanthate: C ₅ H ₁₁ —O—C (═S) —S ^— K so that the amount of amyl xanthate added is 480 mg (solid content) per liter. ⁺ ) Was added and stirred under a residence time of 30 minutes.
Next, the slurry is guided from the hydrophobization reaction tank 6 to the FW type flotation machine 9 through the flow path, and then the slurry is floated in the FW type flotation machine 9 while supplying air, and the floatation is performed. And the deposit was obtained. In addition, when guiding the slurry to the FW type flotation machine 9, as a foaming agent from the foaming agent storage tank 8 at a predetermined point in the flow path, an addition amount of 70 mg per liter of slurry is obtained. Methyl isobutyl carbinol (MIBC) was added.
The content of lead and calcium was measured for each of floatation and sedimentation obtained by flotation. As a result, the ratio of lead recovered from the fine powder A as floating ore (lead recovery rate) was as shown in FIG.

[Example 2]
An experiment was conducted in the same manner as in Example 1 except that fine powder C was used instead of fine powder A. The lead recovery rate was as shown in FIG.
[Example 3]
An experiment was conducted in the same manner as in Example 1 except that fine powder D was used instead of fine powder A. The lead recovery rate was as shown in FIG.

[Example 4]
Using the continuous processing system shown in FIG. 3, the fine powder A was processed as follows.
Water and fine powder A in an amount of 150 g per liter of water were put into the mixing tank 1 equipped with a stirring blade and stirred to obtain a uniform slurry.
After introducing this slurry into a lead sulfide production tank 2 (capacity: 90 liters) equipped with a stirring blade, the amount of sodium hydrosulfide added at 3,000 mg (solid content) per liter of slurry to the slurry in the tank Then, a sodium hydrosulfide aqueous solution (concentration: 20% by mass) was added and stirred under a residence time of 30 minutes to generate lead sulfide (including lead sulfide).
Next, after this slurry is guided to the calcium sulfate production tank 4 (capacity: 45 liters) with a stirring blade, the molar ratio of H ₂ SO ₄ / CaO becomes the value shown in FIG. 5 with respect to the slurry in the tank. An amount of sulfuric acid (concentration: 98% by mass) was added and stirred for a residence time of 30 minutes to produce calcium sulfate. The amount of sulfuric acid added was six variables as shown in FIG. Experiments were performed on each of these six variables.
The pH of the slurry in the calcium sulfate production tank 4 (measured value by the pH measuring means 10) is 6.0 when the H ₂ SO ₄ / CaO molar ratio is the minimum 0.75, and H ₂ SO _{When the 4} / CaO molar ratio was 1.13, the maximum, it was 1.5.

Next, after introducing this slurry into a hydrophobizing reaction tank 6 (capacity: 45 liters) with a stirring blade, slurry 1 was used as a collection agent for increasing the hydrophobicity of lead sulfide with respect to the slurry in the tank. The aqueous amyl xanthate solution was added so that the amount of amyl xanthate added was 480 mg (solid content) per liter, and the mixture was stirred under a residence time of 30 minutes.
Next, the slurry is guided from the hydrophobization reaction tank 6 to the FW type flotation machine 9 through the flow path, and then the slurry is floated in the FW type flotation machine 9 while supplying air, and the floatation is performed. And the deposit was obtained. In addition, when guiding the slurry to the FW type flotation machine 9, as a foaming agent from the foaming agent storage tank 8 at a predetermined point in the flow path, an addition amount of 70 mg per liter of slurry is obtained. Methyl isobutyl carbinol (MIBC) was added.
The content of lead and calcium was measured for each of floatation and sedimentation obtained by flotation. As a result, the lead recovery rate was as shown in FIG.
In addition, in the case where sulfuric acid was added so that the molar ratio of H ₂ SO ₄ / CaO was 1.02, the lead distribution ratio to the float was 75% by mass. The contents of Ca and Pb in the float were 7.7% by mass and 35.8% by mass, respectively.

[Example 5]
An experiment was conducted in the same manner as in Example 4 except that fine powder C was used instead of fine powder A. The lead recovery rate was as shown in FIG.
The pH of the slurry in the calcium sulfate production tank 4 is 7.0 when the molar ratio of H ₂ SO ₄ / CaO is 0.90 which is the minimum, and the molar ratio of H ₂ SO ₄ / CaO is When the maximum was 1.09, it was 2.0.
Moreover, when sulfuric acid was added so that the molar ratio of H ₂ SO ₄ / CaO was 1.02, the distribution ratio of lead to the float was 68% by mass. The contents of Ca and Pb in the float were 15.4% by mass and 15.5% by mass, respectively.

[Example 6]
An experiment was conducted in the same manner as in Example 4 except that fine powder D was used instead of fine powder A. The lead recovery rate was as shown in FIG.
The pH of the slurry in the calcium sulfate production tank 4 is 6.0 when the molar ratio of H ₂ SO ₄ / CaO is 0.84, which is the minimum, and the molar ratio of H ₂ SO ₄ / CaO is When the maximum was 1.11, it was 1.5.
Further, when sulfuric acid was added so that the molar ratio of H ₂ SO ₄ / CaO was 1.02, the distribution ratio of lead to the float was 65% by mass. The contents of Ca and Pb in the float were 16.3% by mass and 9.2% by mass, respectively.

[Comparative Example 1]
In the continuous processing system shown in FIG. 3, a system in which the lead sulfide generator (reference numerals 2 and 3) and the calcium sulfate generator (reference numerals 4 and 5) are reversed is used, and the fine powder is changed to fine powder A. The experiment was performed in the same manner as in Example 1 except that B was used. The lead recovery rate was as shown in FIG.
[Comparative Example 2]
An experiment was conducted in the same manner as in Comparative Example 1 except that fine powder C was used instead of fine powder B. The lead recovery rate was as shown in FIG.
[Comparative Example 3]
An experiment was conducted in the same manner as in Comparative Example 1 except that fine powder D was used instead of fine powder B. The lead recovery rate was as shown in FIG.

[Comparative Example 4]
In the continuous processing system shown in FIG. 3, a system in which the lead sulfide generator (reference numerals 2 and 3) and the calcium sulfate generator (reference numerals 4 and 5) are reversed is used, and the fine powder is changed to fine powder A. The experiment was performed in the same manner as in Example 4 except that B was used. The lead recovery rate was as shown in FIG.
The pH of the slurry in the lead sulfide production tank 2 (measured value by the pH measuring means 10) is 5.0 when the molar ratio of H ₂ SO ₄ / CaO is 0.73, which is the minimum, The H ₂ SO ₄ / CaO molar ratio was 1.5 when the maximum was 1.12.
Further, when sulfuric acid was added so that the molar ratio of H ₂ SO ₄ / CaO was 0.92, the distribution ratio of lead to the float was 65.0% by mass. Moreover, the content rates of Ca and Pb in the float were 8.5% by mass and 27.5% by mass, respectively.

[Comparative Example 5]
An experiment was conducted in the same manner as in Comparative Example 4 except that fine powder C was used instead of fine powder B. The lead recovery rate was as shown in FIG.
The pH of the slurry in the lead sulfide production tank 2 is 6.0 when the H ₂ SO ₄ / CaO molar ratio is 0.88, which is the minimum, and the H ₂ SO ₄ / CaO molar ratio. Was 2.0 when the maximum was 1.06.
Further, when sulfuric acid was added so that the molar ratio of H ₂ SO ₄ / CaO was 1.01, the distribution ratio of lead to the float was 59.0% by mass. The contents of Ca and Pb in the float were 14.7% by mass and 11.3% by mass, respectively.

[Comparative Example 6]
The experiment was performed in the same manner as in Comparative Example 4 except that the fine powder D was used instead of the fine powder B. The lead recovery rate was as shown in FIG.
The pH of the slurry in the lead sulfide production tank 2 is 6.0 when the molar ratio of H ₂ SO ₄ / CaO is 0.78, which is the minimum, and the molar ratio of H ₂ SO ₄ / CaO. Was 1.5 when the maximum was 1.09.
In addition, when sulfuric acid was added so that the molar ratio of H ₂ SO ₄ / CaO was 1.01, the distribution ratio of lead to the float was 68.0% by mass. The contents of Ca and Pb in the float were 17.9% by mass and 8.0% by mass, respectively.
4 to 7, it can be seen that Examples 1 to 6 have higher lead recovery rates and are more stable than Comparative Examples 1 to 6 regardless of the amount of sulfuric acid added.

It is a flowchart which shows an example of the processing method of the fine powder of this invention. It is a flowchart which shows the processing method of the fine powder in a comparative example. It is a flowchart which shows an example of the processing system of the fine powder of this invention. It is a graph which shows the relationship between the value of the pH of the slurry (in the hydrophobization reaction tank) and the recovery rate of lead in Examples 1 to 3. It is a graph showing the relationship between the addition amount _{(H 2} SO 4 / CaO molar ratio) and recovery of lead sulfate in Examples 4-6. It is a graph which shows the relationship between the value of the pH of the slurry (in the hydrophobization reaction tank) and lead recovery in Comparative Examples 1 to 3. The addition amount of sulfuric acid in Comparative Example 4-6 _(molar ratio of H ₂ SO 4 / CaO) and is a graph showing the relationship between the recovery of lead.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mixing tank 2 Lead sulfide production tank 3 Sulfide storage tank 4 Calcium sulfate production tank 5 Sulfuric acid storage tank 6 Hydrophobization reaction tank 7 Collection agent storage tank 8 Foaming agent storage tank 9 Flotation machine 10 pH measuring means

Claims (2)

(A) a lead sulfide production step of obtaining a slurry containing lead sulfide that is a solid component by mixing a fine powder containing a calcium component and a lead component, water, and a sulfurizing agent;
(B) The sulfuric acid is added to the slurry obtained in the step (A) to adjust the pH of the slurry to 1.5 to 7.5 to obtain a slurry containing lead sulfide and calcium sulfate as solid components. A calcium sulfate production process;
(C) a lead sulfide hydrophobizing step of adding a collector to the slurry obtained in step (B) to hydrophobize the lead sulfide in the slurry;
(D) A lead / calcium separation step of subjecting the slurry obtained in step (C) to a flotation process to obtain a float containing lead sulfide and a deposit containing calcium sulfate;
The processing method of the fine powder containing the calcium component and lead component characterized by including these. A lead sulfide generator for obtaining a slurry containing lead sulfide, which is a solid component, by mixing fine powder containing calcium and lead components, water, and a sulfurizing agent;
Calcium sulfate generator for obtaining a slurry containing lead sulfide and calcium sulfate as solids by adding sulfuric acid to the slurry obtained by the lead sulfide generator;
A lead sulfide hydrophobizing device for hydrophobizing lead sulfide in the slurry by adding a collector to the slurry obtained by the calcium sulfate generating device;
A flotation device for flotation of the slurry obtained by the lead sulfide hydrophobization device;
A processing system for fine powder containing a calcium component and a lead component.

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