JPH1110131A - Method for recovery of heavy metals from soil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To purify soil economically by recovering heavy metals from soil by a method wherein water is added to the soil contaminated with heavy metals such as lead or the like to make slurry, and after adding one kind or two or more kinds selected from a collector, a foaming agent, and a conditioning agent, the slurry is treated with flotation. SOLUTION: Contaminated soil extracted from a bin 1 is weighed with a load cell, and sent to a rod mill 4 with a belt conveyor 3. The soil ground with the rod mill 4 is sent to a primary cyclone 6 with a pump 5 to be classified, and the classified undersize is sent back to the rod mill 4. Besides, a cyclone oversize is sent to a secondary cyclone 8 with a pump 7 to be classified, and the oversize is sent to a roughing flotation conditioner 10. Then, pulp conditioned with the roughing flotation conditioner 10 is sent to a flotation device 11 to execute flotation, the roughed float is sent to a cleaning flotation device 16 through cleaning conditioners 14, 15 to execute cleaning flotation, and cleaned float is recovered as the concentrate after dewatering with a dewatering tank 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for separating and recovering heavy metals from soil contaminated with heavy metals and purifying the soil. More specifically, the present invention relates to a method for flotation to convert heavy metals from soil to flotation. The present invention relates to a method for recovering heavy metals from soil that separates and collects and recycles and purifies the soil.

[0002]

2. Description of the Related Art In recent years, the removal of pollutants in the industry,
With the increase in pollution control activities, concerns about environmental pollution caused by new chemical substances and the problem of soil pollution including harmful substances accumulated in the past have been highlighted in connection with the problem of waste disposal that is increasing rapidly. Therefore, it is necessary to take measures to purify contaminated soil by removing harmful substances in accordance with the “Soil Environmental Standards”.

[0003] As a means for repairing soil contaminated with heavy metals, a method of confining after carrying out chemical treatment or a method of solidifying with concrete, and as a physical measure, discharging surface soil to a certain depth, There are known treatment methods for removing soil that is not contaminated on the discharged surface.

[0004] However, the conventional chemical treatment and physical countermeasures have problems such as high chemical costs and soil transportation costs.

On the other hand, various methods have been proposed and known for separating heavy metals from soils actually contaminated with heavy metals. Known methods for separating heavy metals, for example, separation by complex chloride or separation by ion exchange, have been proposed. Alternatively, none of the removal methods of dissolving heavy metals with a mineral acid and separating them as hydroxides are satisfactory, and these methods are too expensive for chemicals or equipment or the separation process is not sufficiently effective. There are problems such as not.

As described above, no technique has been established for recovering and recycling heavy metals from soil contaminated with heavy metals, and therefore there has been a demand for an economically inexpensive and effective treatment method.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and purifies and repairs soil contaminated with heavy metals. -To recover and recycle, the present invention proposes a method for separating and recovering heavy metals and purifying the soil economically and efficiently by flotation treatment of soil containing the contaminants.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, as a method of purifying contaminated soil, recovering and recycling heavy metals from soil contaminated with heavy metals. Inexpensive physical treatment method could be developed.

That is, the first invention is to add water to a soil contaminated with heavy metals such as lead to form a slurry, and to collect one or more selected from a collecting agent, a foaming agent, and a conditioning agent. Is a method for recovering heavy metals from soil, comprising separating the heavy metals from the soil by flotation of the slurry to purify the soil while purifying the soil. ,

A second aspect of the present invention is to grind the soil particles contaminated with heavy metals such as lead to a particle size of 100 μm or less, and then add water to form a slurry, and select from a collecting agent, a foaming agent, and a conditioning agent. A soil characterized by separating one or more heavy metals from the soil to recover the heavy metals and purifying the soil by flotation of the slurry after adding one or more selected one or two or more conditions. Is a method of recovering heavy metals from

According to a third aspect of the present invention, a soil contaminated with heavy metals such as lead is slurried by adding water, a sulphating agent is added or blown, and then a collecting agent, a foaming agent and a conditioning agent are selected. After adding one or two or more of the conditions described above, the slurry is subjected to flotation to separate heavy metals from the soil to recover the heavy metals and to purify the soil. Is a method of recovering heavy metals

[0012] A fourth aspect of the present invention is to pulverize the soil particles contaminated with heavy metals such as lead to a particle size of 100 µm or less, then add water to make a slurry, and add or blow a sulphidizing agent. After adding one or more kinds selected from a foaming agent and a conditioning agent, conditions are added, and the slurry is subjected to flotation to separate heavy metals from the soil to recover the heavy metals and to remove the soil. It is intended to provide a method for recovering heavy metals from soil, which is characterized by purifying water.

[0013] In the above invention, the soil particles may be 10
The crusher for crushing to 0 μm or less is preferably a rod mill and / or a ball mill, and the collector used is dialkyldithiocarbamate, xanthate,
It is preferable that the agent is a drug containing any of dialkyldithiophosphates, that the conditioner is an acid or an alkali, and that the sulphidating agent is any of sodium sulfide, sodium hydrosulfide or hydrogen sulfide. is there.
Next, embodiments of the present invention will be described with reference to the drawings.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In soil contamination by heavy metals, contaminants may be present as fine precipitates in the interstices between soil particles, or may be adsorbed on a part of soil particles or on clay having high cation exchange capacity. Or heavy metals may be mixed in the form of metal powder. Therefore, the present invention is characterized in that soil contaminated with heavy metals is treated with a flotation machine to concentrate and separate heavy metals into flotation.

In the present invention, flotation is preferably performed on the contaminated soil to be treated, preferably after concentration of heavy metals by classification or the like. There are features.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the technical scope of the present invention is not limited thereto.

Example 1 A 500 g sample obtained by crushing heavy metal-contaminated soil in Area A with a crusher into -35 mesh (0.417 mm) was put into a pot mill, 750 cc of water was added, and ground and pulverized for 40 minutes.
The average particle size of the soil particles was set to 100 μm or less. This pulp is transferred to Kyoto University flotation machine (1800cc, 12,500rpm)
m), and 150 g / t of sodium diethyldithiocarbamate as a collecting agent and 200 g / t of "Niska # 125" (trade name) manufactured by Nippon Perfume Co., Ltd. as a foaming agent were added, and conditioning was performed for 10 minutes. After that, rough flotation was performed for 15 minutes. For flotation, Pb concentrate was collected by performing flotation (pH 10.6) for another 5 minutes. The result of the separation result is as shown in FIG.

Example 2 The same sample as in Example 1 was used except that the collector was added to 50 g / t of amyl xanthate after sulfided with sodium hydrosulfide during flotation using the same sample as in Example 1. Separated by operation. The result of the separation result is as shown in FIG.

Example 3 FIG. 3 shows a flow sheet when contaminated soil in the area A is treated in a beneficiation plant, and FIG. 4 shows a material balance at this time. explain.

The contaminated soil extracted from the bin 1 is weighed by the load cell 2 and is fed at a speed of 9 t / h to the belt conveyor 3.
And sent to the rod mill (8 ′ × 13 ′) 4.
The soil ground and crushed by the rod mill 4 (the average particle diameter of the crushed soil is 100 μm or less) is sent to the primary cyclone (MD6 × 3) 6 by the pump 5 and classified.

The classified under is repeated to the rod mill 4. The cyclone over is sent to a secondary cyclone 8 by a pump 7, and the classified over is sent to a rough-selection flotation conditioner (1,5 mφ) 10. The secondary cyclone under is repeated in the ball mill (5 '× 10') 9. Sodium diethyldithiocarbamate as a collecting agent and "Nisuka # 125" (trade name) as a foaming agent were added to the rough flotation conditioner, and conditioning was performed for 5 minutes.

In the present invention, the collecting agent is not particularly limited, but heavy metals contained in the soil are mostly metals and oxides, and ordinary sulfide mineral flotation cannot be applied. Therefore, it is preferable to sulfurate with a sulfurizing agent and then treat with xanthate or dithiocarbamate.

The pulp conditioned by the coarse-selection conditioner 10 is sent to a # 24FW flotation machine (number of cells: 8 wards) to perform a coarse-selection flotation. The coarse sediment is sent to a waste thickener by a pump 13. On the other hand, the coarse flotation is sent to # 18FW (fourth ward) 16 through the fine conditioners 14 and 15 to perform the fine flotation, and the fine flotation is sent to the dewatering tank 19 to be recovered as a concentrate after dehydration. You. On the other hand, the selective smelting is repeated to the coarse conditioner 10 by the pump 17.

As a result, as shown in FIG. 4, 15.6% of lead concentrate could be recovered from the soil contaminated with heavy metals by the method of the present invention.

In the above embodiment, P was used as the heavy metal.
b, but the present invention is of course applied to Cd, As, Hg, etc., and the analysis values in the test soil, flotation sediment, and Pb concentrate in Example 3 were used. Is also illustrated in FIG. In addition, it was found that the soil after collecting the heavy metals was below the content reference value in the “Guidelines for Soil Pollution Investigation and Countermeasures Related to Heavy Metals” disclosed in the Water Quality Conservation Bureau of the Environment Agency shown in Table 1.

[0026]

[Table 1]

[0027]

As described above, the method of the present invention recovers high-grade heavy metals from contaminated soil, which has rarely been neglected, and also makes it possible to purify the soil, thereby preventing secondary pollution and reusing resources. Above is very useful.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing separation results of Example 1 according to the present invention.

FIG. 2 is an explanatory diagram showing separation results of Example 2 according to the present invention.

FIG. 3 is a view showing a flow sheet performed in Example 3 (Pb intermediate concentrate flotation test) according to the present invention.

FIG. 4 is a diagram illustrating a material balance according to a third embodiment of the present invention.

[Explanation of symbols]

 1-bin 2-load cell 3-belt conveyor 4-rod mill 5-pump (1) 6-primary cyclone 7-pump (2) 8-secondary cyclone 9-ball mill 10-coarse conditioner 11-coarse flotation machine 12-pump (3) 13-pump (4) 14-selection conditioner (1) 15-selection conditioner (2) 16-selection flotation machine 17-pump (5) 18-pump (6) 19-dehydration tank

Continued on front page (72) Inventor Ikuo Kirikoshi 42 Hazukazawa, Hanaoka-cho, Odate-shi, Akita Hanaoka Mining Co., Ltd.

Claims (8)

[Claims] 1. Soil contaminated with heavy metals such as lead is slurried by adding water, and one or more selected from a collecting agent, a foaming agent, and a conditioning agent are added and conditions are provided. rear,
A method for recovering heavy metals from soil, comprising separating heavy metals from soil by flotation of the slurry to recover heavy metals and purifying the soil. 2. A soil particle contaminated with heavy metals such as lead is crushed to a particle size of 100 μm or less, and then water is added to form a slurry, which is selected from a collecting agent, a foaming agent, and a conditioning agent.
After adding seeds or two or more kinds and adding conditions, the slurry is subjected to flotation to separate heavy metals from the soil to recover the heavy metals and to purify the soil. Collection method. 3. Soil contaminated with heavy metals such as lead is slurried by adding water, and a sulphating agent is added or blown, and then one or more selected from a collecting agent, a foaming agent, and a conditioning agent. After adding and adding two or more kinds of conditions, the slurry is subjected to flotation to separate heavy metals from the soil to recover the heavy metals and to purify the soil. Collection method. 4. Soil particles contaminated with heavy metals such as lead are pulverized to a particle size of 100 μm or less, and then slurried by adding water, and a sulphating agent is added or blown in, followed by a collecting agent, a foaming agent, After adding one or two or more selected from the conditioning agents and applying conditions, the slurry is subjected to flotation to separate heavy metals from soil to recover heavy metals and to purify the soil. A method for recovering heavy metals from soil, characterized in that: 5. The method for recovering heavy metals from soil according to claim 2, wherein the crusher for crushing the soil particles to 100 μm or less is a rod mill and / or a ball mill. 6. The collecting agent according to claim 1, wherein the collecting agent contains at least one of dialkyldithiocarbamate, xanthate, and dialkyldithiophosphate.
4. The method for recovering heavy metals from soil according to 4. 7. The method for recovering heavy metals from soil according to claim 1, wherein the conditioning agent is an acid or an alkali. 8. The method for recovering heavy metals from soil according to claim 3, wherein the sulfurizing agent is sodium sulfide, sodium hydrosulfide or hydrogen sulfide.