JP6864648B2 - Raw material recovery method for valuable metal refining - Google Patents

Description

The present invention relates to a marketable raw material recovery method for metal refining, particularly municipal waste incineration ash, a method of recovering valuable metals contained in waste such as sludge.

Conventionally, electronic substrates used in home appliances are recycled to recover valuable metals such as gold, silver, copper, tin, and nickel. In addition, mercury is being recovered through the recycling of mercury lamps and fluorescent lamps.

Further, in Patent Document 1, waste such as municipal waste is crushed by a crusher, water is removed by a dryer as necessary, and pyrolysis is carried out in a pyrolysis furnace to generate a pyrolysis residue, which is then pyrolyzed. After sorting the char from the residue with a sorting device, it is pulverized with a pulverizing device, and the pulverized char is transferred by a transfer means and burned as fuel in another facility, so that high-quality valuable metals and glasses can be recovered. A method of using fuel for goods has been proposed.

Further, in Patent Document 2, fly ash is dechlorinated and washed, and the dechlorinated fly ash, zinc-containing raw material, flux and coal are mixed, dried and crushed to form an aggregate, and the aggregate is used as an aggregate. A method for recovering valuable metals by melt-reduction is described.

Japanese Unexamined Patent Publication No. 2000-283430 Japanese Unexamined Patent Publication No. 2007-186761

However, in the above-mentioned conventional technique, a large amount of energy is consumed for drying and crushing waste and heat treatment, so that the operating cost rises. On the other hand, when a small-scale batch type collection device is used, there is a problem that it is difficult to realize from the viewpoint of profitability.

Therefore, the present invention has been made in view of the above problems, and while effectively utilizing wastes such as municipal waste incineration ash and sludge as cement raw materials, the valuable metals contained in these wastes can be used at low cost. The purpose is to collect it at.

In order to achieve the above object , the present invention is a method for recovering raw materials for refining valuable metals, in which ordinary Portland cement is produced by using city waste incineration ash as a part of cement raw materials in an amount of 20 kg or more per ton of a cleaner to produce cement. A part of the combustion gas is extracted from the kiln exhaust gas flow path from the kiln kiln end to the bottom cyclone while cooling, and the extracted gas is separated into solid air and is a raw material for refining valuable metals containing 150 mg / kg or more of silver. It is characterized by collecting.

According to the present invention, a raw material for refining valuable metals can be obtained from waste such as municipal waste incineration ash without incurring a recovery cost in the process of treating exhaust gas from a cement kiln. In addition, waste can be effectively used and resources with high scarcity value can be saved.

As described above, according to the present invention, a raw material for refining valuable metals can be obtained without incurring a recovery cost or at a low cost.

It is an overall block diagram which shows one Embodiment of the cement kiln bleeding dust processing apparatus to which the raw material recovery method for valuable metal refining which concerns on this invention is applied. It is a flowchart for demonstrating the HMX processing process in the cement kiln bleeding dust processing apparatus of FIG.

Next, a mode for carrying out the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cement kiln bleeding dust treatment device to which the method for recovering raw materials for smelting valuable metals according to the present invention is applied. It is composed of a powder processing unit 4.

The gas extraction unit 2 is a facility for extracting a part of combustion gas from the kiln exhaust gas flow path from the kiln bottom of the cement kiln 5 to the lowermost cyclone (not shown). The gas extraction unit 2 includes a probe 6 that extracts combustion gas, a cooling fan 7 that supplies cold air into the probe 6 to quench the extracted combustion gas, and dust contained in the extraction gas G1 discharged from the probe 6. It is composed of a cyclone 10 or the like as a classifier for separating the coarse powder D1 inside.

The gas treatment unit 3 is a facility for collecting fine powder D2 contained in the exhaust gas G2 discharged from the cyclone 10. The gas processing unit 3 includes a cooler 11 that cools the exhaust gas G2 containing the fine powder D2 discharged from the cyclone 10, a cooling fan 12 that supplies cold air to the cooler 11, and the exhaust gas G3 cooled by the cooler 11. A bag filter 13 for collecting the dust D4 and a dust tank 14 for collecting the dusts D3 and D4 discharged from the cooler 11 and the bag filter 13 are provided.

The fine powder processing unit 4 is a facility for washing the chlorine bypass dust D5 stored in the dust tank 14 with water, treating it with HMX, and performing flotation.

The fine powder processing unit 4 solid-liquid separates the dissolution tank 20 for washing the chlorine bypass dust D5 stored in the dust tank 14 with water under acidic conditions and the slurry S1 generated by washing with water in the dissolution tank 20. The separator 21 and the HMX treatment step 22 for HMX-treating the cake C1 obtained by the first solid-liquid separator 21 and the cake C2 discharged from the HMX treatment step 22 are added with a sulfide and water to form a slurry. The slurry tank 23, the adjusting tank 24 for adding a pH adjusting agent such as sulfuric acid to the slurry S2 generated in the slurry tank 23, and the adjusting tank 25 for adding a hydrophobic agent as a collecting agent to the slurry S3 after adjusting the pH. And.

Further, the fine powder processing unit 4 has a flotation machine 26 in which the sulfide in the slurry S4 is attached to bubbles to float and separate the sulfide, and a second solid-liquid separation of the floss F from the flotation machine 26. The separator 27, the adjusting tank 28 for adjusting the pH by adding an alkaline agent to the tail T from the flotation machine 26, and the third solid-liquid separator 29 for solid-liquid separating the slurry S5 from the adjusting tank 28. It is composed.

The HMX treatment step 22 is provided for recovering a higher quality valuable metal refining raw material from the cake C1 obtained by the first solid-liquid separator 21, and as shown in FIG. 2, water is added to the cake C1. A water washing step of adding water and washing with water, an acid leaching step of acid leaching the slurry S6 after washing with water and sulfuric acid, and alkaline leaching of adding caustic soda to the slurry S7 after acid leaching to make it alkaline. It consists of processes.

Next, the method for recovering raw materials for refining valuable metals according to the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, the cement raw material supplied to the preheater (not shown) attached to the cement kiln 5 is preheated by the preheater, calcined in a calcining furnace (not shown), and then fired in the cement kiln 5. Will be done.

As the cement raw material, in addition to general-purpose raw materials (limestone, clay, iron slag, etc.), various wastes such as incineration main ash, incineration fly ash, sludge, and shredder dust are used. For example, it has been confirmed that the incinerated main ash and the incinerated fly ash contain 0.1 to 4 ppm of gold, 5 to 50 ppm of silver, and 1 to 50 ppm of bismuth. The amount of incinerated main ash and incinerated fly ash used is preferably 10 kg or more, more preferably 20 kg or more per ton of clinker. By using 10 kg or more, the concentration of gold, silver and bismuth of chlorine bypass dust becomes high, and it becomes more useful as a raw material for refining.

When a part of the combustion gas is extracted by the probe 6 from the kiln exhaust gas flow path from the kiln tail of the cement kiln 5 to the lowermost cyclone, microcrystals of volatile components in the combustion gas are generated and contained in the extracted gas G1. Since valuable metals are unevenly distributed on the fine powder side of the dust, the crude powder D1 classified by the cyclone 10 is returned to the cement kiln system. On the other hand, the bleed air gas G2 containing the fine powder D2 separated by the cyclone 10 is introduced into the heat exchanger 11 to exchange heat between the bleed air gas G2 and the medium. The bleed air G3 cooled by heat exchange is introduced into the bug filter 13, and the dust D4 contained in the bleed air G3 is recovered by the bag filter 13. The dust D4 collected by the bag filter 13 is temporarily stored in the dust tank 14 together with the dust D3 discharged from the heat exchanger 11.

The chlorine bypass dust D5 (D3 + D4) stored in the dust tank 14 contains chlorine and gold and silver precious metals derived from various wastes such as incineration main ash. The chlorine bypass dust D5 can increase the valuable metal concentration by preferably 10% by mass or more, more preferably 15% or more, using the chlorine concentration as a guide.

As the amount of chlorine bypass dust D5 passing through 10 μm increases, the coarse powder D1 containing calcium and silicon is removed and the concentration of valuable metals increases. Therefore, the classification point of the cyclone 23 is adjusted to pass the amount of dust D5 passing through 10 μm to 80. It is preferably mass% or more.

Further, the amount of the extracted gas G1 (extracted amount) in the chlorine bypass equipment 1 is preferably 0.1 to 20% of the combustion gas flowing through the kiln exhaust gas flow path. The reason why the upper limit of the amount of extracted air is set to 20% is that the heat loss is large, the stable operation of the kiln cannot be ensured economically, and the concentration of valuable metals decreases. On the other hand, the lower limit of the extraction amount is set to 0.1% in order to recover more valuable metal without being discharged to the cement clinker.

Since calcium and silicon are contained in a large amount in the crude powder D1, chlorine bypass dust D5, which has a low concentration of calcium and silicon and a high concentration of valuable metals, is generally used as a raw material for cement by using chlorine bypass dust D5 as a raw material for refining valuable metals. It is possible to obtain a raw material for refining valuable metals, which has a valuable metal concentration several times higher than that of incinerated municipal waste ash.

Next, in the dissolution tank 20, the chlorine bypass dust D5 from the dust tank 14 can be washed with water. Chlorine bypass dust D5, a filtrate W2 for washing with water, and an acid can be supplied to the dissolution tank 20, and the chlorine bypass dust D5 can be washed with water under acidic conditions. By adding hydrochloric acid or nitric acid, it is possible to prevent the formation of gypsum, which causes a decrease in the concentration of valuable metals. Further, it is preferable to add hydrochloric acid to prevent the elution of silver.

Next, the slurry S1 produced in the melting tank 20 is solid-liquid separated by the first solid-liquid separator 21, the slurry S1 is separated into a filtrate W1 and a cake C1, and the separated cake C1 is used as it is for valuable metal refining. It can also be used as a raw material. The filtrate W1 is sent to the final wastewater treatment process.

As shown in FIG. 2, the cake C1 is washed with water, the waste liquid W4 containing the alkaline salt generated by the washing is introduced into the final wastewater treatment step, and the slurry S6 after the washing is acid-leached using water and sulfuric acid. , The slurry S7 obtained by acid leaching is made alkaline by adding caustic soda, and the cake C2 obtained by solid-liquid separation of the slurry S7 is supplied to the slurry tank 23. The cake produced in the final wastewater treatment process is used as a raw material for cement or disposed of. It is also possible to omit washing with water and supply chlorine bypass dust D5 instead of cake C1.

Further, since cake C2 has alkali salts, copper, lead, zinc and the like removed by HMX treatment, by using cake C2 as a raw material for valuable metal refining, a higher quality raw material for valuable metal refining can be obtained. Can be done.

Next, water and a sulfurizing agent are added to the slurry tank 23 to which the cake C2 has been supplied to generate the slurry S2, and the slurry S2 is supplied to the adjusting tank 24. Further, in the adjusting tank 24, sulfuric acid or hydrochloric acid is added to the slurry S2 as a pH adjusting agent to adjust the pH value of the slurry S2 to 2 to 4, and then the slurry S3 having the adjusted pH value is supplied to the adjusting tank 25. .. Further, a hydrophobizing agent as a collecting agent is added in the adjusting tank 25. It is also possible to omit washing with water and HMX treatment and supply chlorine bypass dust D5 or cake C1 instead of cake C2.

Next, the slurry S4 to which the hydrophobizing agent is added and air are supplied to the flotation machine 26, and bubbles are generated in the flotation machine 26 to attach sulfides to the bubbles, and sulfides such as silver and bismuth are generated. The bubbles that have adhered and floated, that is, the sulfide F, are collected. At this time, the gypsum contained in the slurry S4 is discharged as the tail T from the flotation machine 26.

Next, in the second solid-liquid separator 27, the floss F from the flotation machine 26 is solid-liquid separated to produce cake C3, and the raw material for valuable metal refining is recovered. This makes it possible to recover raw materials for refining valuable metals, which have a particularly high concentration of silver and bismuth. The filtrate W2 generated at this time is sent to the final wastewater treatment step or supplied to the dissolution tank 20 to be used for adjusting the solid-liquid ratio of the slurry in the dissolution tank 20.

At the same time, the tail T of the flotation machine 26 is supplied to the adjusting tank 28, the pH of the tail T is adjusted by adding an alkaline agent, and residual heavy metals such as cadmium are precipitated. As the alkaline agent, slaked lime, sodium hydroxide, barium hydroxide and the like can be used. Furthermore, when slaked lime is used as the alkaline agent, fluorine and sulfate roots can be precipitated and removed from the liquid. In this case, troubles due to the circulation of sulfate roots in the system can be avoided. In particular, by removing the sulfate root, it is possible to avoid problems such as coaching growth in the cement manufacturing process and an increase in SOx concentration in the exhaust gas.

The slurry S5 produced in the adjusting tank 28 can be supplied to the third solid-liquid separator 29, and the precipitated heavy metals and gypsum S can be recovered on the cake C4 side. This gypsum S contains heavy metals, but it does not matter because it is a very small amount. Further, the filtrate W3 is treated in the final wastewater treatment step. The cake produced in the final wastewater treatment process is used as a raw material for cement or disposed of.

As described above, according to the present embodiment, a raw material for refining valuable metals can be obtained from waste such as municipal waste incineration ash without incurring recovery costs or at low cost in the process of treating exhaust gas from a cement kiln. Can be done. In addition, since chlorine bypass dust can be effectively used, more waste can be used as a raw material for cement, and resources of rare gold, silver, and bismuth can be saved.

In the above embodiment, after the coarse powder D1 is classified by the cyclone 10, the exhaust gas G2 containing the fine powder D2 is introduced into the bag filter 13 via the cooler 11, but the probe 6 is not provided with the cyclone 10. The extracted gas G1 extracted in 1 may be directly introduced into the bug filter 13 via the cooler 11. Further, it is also possible to use a bug filter 13 capable of processing high temperature gas and not to install a cooler 11. Further, instead of supplying the filtrate W2 to the dissolution tank 20, it is also possible to newly supply industrial water.

Further, in the above embodiment, the fine powder D2 is dry-type dust collected using the bag filter 13, but the fine powder D2 may be made into a slurry while adding water and a sulfurizing agent via a wet dust collector such as a scrubber.

At the A cement factory, 20 kg of municipal waste incineration ash was used per ton of clinker, and other waste and limestone were also used to produce ordinary Portland cement. As a result, in the chlorine bypass facility 1 shown in FIG. 1, chlorine bypass dust D5 having Au: 2 mg / kg, Ag: 150 mg / kg, Bi: 160 mg / kg, CaO: 41% by mass, and Cl: 18% by mass was obtained. ..

At the B cement factory, 40 kg of municipal waste incineration ash was used per ton of clinker, and other waste and limestone were also used to produce ordinary Portland cement. As a result, in the chlorine bypass facility 1 shown in FIG. 1, chlorine bypass dust D5 having Au: 6 mg / kg, Ag: 380 mg / kg, Bi: 170 mg / kg, CaO: 14% by mass, and Cl: 30% by mass was obtained. ..

In this way, the chlorine bypass dust D5 obtained has a concentration of gold, silver, and bismuth that is several times higher than that of incinerated ash, and is several times higher than that of general natural ore.

3 parts by mass of water was mixed with 1 part by mass of chlorine bypass dust obtained in Example 2 (B cement factory), stirred for 30 minutes, and then dehydrated and dried. As a result, washing dust of Au: 10 mg / kg, Ag: 940 mg / kg, and Bi: 350 mg / kg was obtained.

3 parts by mass of water was mixed with 1 part by mass of chlorine bypass dust obtained in Example 2 (B cement factory), hydrochloric acid was added, the mixture was stirred for 30 minutes while maintaining pH 8, and then dehydrated and dried. As a result, hydrochloric acid-treated dust having Au: 14 mg / kg, Ag: 1200 mg / kg, and Bi: 440 mg / kg was obtained.

3 parts by mass of water was mixed with 1 part by mass of chlorine bypass dust obtained in Example 2 (B cement factory), nitric acid was added, the mixture was stirred for 30 minutes while maintaining pH 3, and then dehydrated and dried. As a result, nitric acid-treated dust having Au: 16 mg / kg, Ag: 910 mg / kg, and Bi: 240 mg / kg was obtained.

130 g of chlorine bypass dust and 1300 ml of distilled water obtained in Example 1 (A cement factory) were put into a mixing tank and stirred to obtain a uniform slurry. Since the chlorine bypass dust contains as much lead as 1.7% by mass, an aqueous solution of sodium hydrosulfide (concentration: 10%) is used as a sulfurizing agent so that the molar ratio of sodium hydrosulfide / lead becomes 1.0. In addition to the above, the mixture was stirred to obtain a slurry containing sulfide. Next, hydrochloric acid (concentration: 36%) was added to this slurry and stirred to adjust the liquid property to pH 2.0. An aqueous solution of Zansate (concentration: 5%) was added to this slurry as a hydrophobizing agent, and the mixture was stirred for 15 minutes. The amount of zansate added was such that the molar ratio of zansate / lead was 0.04. Next, this slurry was guided to a first-stage flotation machine and subjected to flotation treatment for 20 minutes. After the treatment, the slurry portion containing the flotation and the slurry portion containing the sedimentation were recovered from the flotation machine.

On the other hand, an aqueous solution of Zansate (concentration: 5%) was added to the slurry portion containing the sediment recovered from the first-stage flotation machine, and the mixture was stirred for 15 minutes. The amount of zansate added was such that the molar ratio of zansate / lead was 0.04. Next, this slurry portion was guided to a second-stage flotation machine and subjected to flotation treatment for 10 minutes. After the treatment, the slurry portion containing the flotation and the slurry portion containing the sedimentation were recovered from the flotation machine.

On the other hand, an aqueous solution of Zansate (concentration: 5%) was added to the slurry portion containing the sediment recovered from the second-stage flotation machine, and the mixture was stirred for 15 minutes. The amount of zansate added was such that the molar ratio of zansate / lead was 0.04. Next, this slurry portion was guided to a third-stage flotation machine and subjected to flotation treatment for 10 minutes. After the treatment, the slurry portion containing the flotation and the slurry portion containing the sedimentation were recovered from the flotation machine.

Three stages of floating ore were recovered and dehydrated and dried. As a result, flotation-treated dust having Ag: 550 mg / kg and Bi: 820 mg / kg was obtained.

Chlorine bypass dust (lead-containing) obtained in Example 2 (B cement factory) in the same manner as in Example 6 except that hydrochloric acid (concentration: 36%) was added to adjust the liquid property to pH 4.0. A flotation treatment (amount of 0.4% by mass) was carried out. As a result, flotation-treated dust having Ag: 1900 mg / kg and Bi: 900 mg / kg was obtained.

1 Processing device 2 Gas extraction unit 3 Gas processing unit 4 Fine powder processing unit 5 Cement kiln 6 Probe 7 Cooling fan 10 Cyclone 11 Cooler 12 Cooling fan 13 Bug filter 14 Dust tank 20 Melting tank 21 First solid-liquid separator 22 HMX processing process 23 Slurry tank 24, 25 Adjustment tank 26 Floating machine 27 Second solid-liquid separator 28 Adjustment tank 29 Third solid-liquid separator C1 to C4 Cake D1 Coarse powder D2 Fine powder D3, D4 Dust D5 Chlorine bypass Dust F Fross G1 Extracted gas G2, G3 Exhaust gas S1 to S7 Slurry T Tail W1 to W3 Filter W4 Waste liquid

Claims (1)

Ordinary Portland cement is manufactured using 20 kg or more of municipal waste incineration ash as part of the cement raw material, and part of the combustion gas from the kiln exhaust gas flow path from the kiln butt of the cement kiln to the bottom cyclone. A method for recovering a raw material for refining a valuable metal, which comprises extracting air while cooling the material, separating the extracted gas into a solid air, and recovering a raw material for refining valuable metal containing 150 mg / kg or more of silver.

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