JPH05177108A - Treatment agent and treatment method for industrial waste containing heavy metals - Google Patents

Abstract

PURPOSE:To provide a treatment agent for industrial waste containing heavy metals generating almost no elution of heavy metals from treated matter and capable of performing treatment in a relatively inexpensive manner. CONSTITUTION:3-20wt.% of sodium silicate, if necessary, 0.5-5wt.% of magnesium oxide and 3-15wt.% of silicon are mixed with 100wt.% of quick lime to obtain a treatment agent for industrial waste containing heavy metals. Herein, at least, quick lime is subjected to oil film treatment. The industrial waste containing heavy metals is treated with this treatment agent. When industrial waste contains no water, water is added to said waste in an amount necessary for the reaction of quick lime.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a plating solution containing heavy metals such as mercury, cadmium, hexavalent chromium and arsenic, or a treatment agent for industrial waste such as sludge containing heavy metals, sludge (including dried products), and the like. Regarding the processing method.

[0002]

2. Description of the Related Art Conventionally, industrial wastes containing heavy metals are discharged from chemical plants or plating plants.
If discharged outside the factory, it will cause pollution. For example, if the industrial waste is a sludge such as sludge, it is recommended that a hardener such as cement be mixed appropriately to solidify and landfill disposal. Has been done. Further, when the industrial waste is a plating waste liquid or the like, a chemical treatment or a physical treatment is appropriately performed, and solid-liquid separation is performed.

[0003]

However, even if hardened materials such as cement are mixed with industrial waste to solidify it and landfill treatment is carried out, heavy metals are not fixed, and if left alone, heavy metals gradually elute. However, there is a problem that environmental pollution gradually occurs. Further, in the case of industrial waste such as a plating solution, performing chemical treatment or physical treatment of the plating solution to perform solid-liquid separation requires an extra step, a treatment device, etc., and is costly. There was a problem. The present invention has been made in view of the above circumstances, and provides a treatment agent and a treatment method for industrial waste containing heavy metals or the like that can be treated at a relatively low price with almost no elution of heavy metals or the like from the treated products. The purpose is to

[0004]

A method according to the above-mentioned object.
The treatment agent for industrial waste containing the described heavy metals is quicklime 1
An external content of 3 to 20% by weight of sodium silicate and, if necessary, 0.5 to 5% by weight of magnesium oxide and 3 to 15% by weight of silicon oxide is mixed with 00% by weight, and at least the quicklime is subjected to an oil film treatment. It has been configured. Further, according to the method for treating industrial waste containing heavy metals or the like according to claim 2, the industrial waste containing heavy metals or the like is treated with 3 to 20% by weight of sodium silicate based on 100% by weight of quick lime. If necessary, a proper amount of a treating agent mixed with 0.5 to 5% by weight of magnesium oxide and 3 to 15% by weight of silicon is mixed, and when the industrial waste does not contain water, the quicklime reacts. Water required for stirring is added and the quicklime is heated to accelerate the temperature of the mixture to accelerate the reaction.
It is configured to insolubilize the heavy metal and the like.

[0005]

In the treating agent for industrial waste containing heavy metals and the like according to claim 1 and the method for treating industrial waste containing heavy metals and the like according to claim 2, quick lime contained in the treating agent is subjected to oil film treatment. Therefore, even if it is left as it is, the reaction that absorbs water and becomes slaked lime is prevented, and it has a long life. Then, when the treating agent is mixed with industrial waste containing water and stirred, the oil film of the quicklime breaks and reacts with water by the following reaction to produce slaked lime (calcium hydroxide). CaO + H ₂ O → Ca (OH) ₂ (1) As a result, the temperature of the mixture rises, but the temperature is about 70 to 100 ° C. when the industrial waste is a liquid, and 100 to 100 ° C. when the industrial waste is a liquid. It is preferable to raise the temperature to 200 ° C. And Hg, Cd, Cr contained in industrial waste
And other heavy metal ions (hereinafter, referred to as M ²⁺ ) and sodium silicate in the treating agent are activated to produce a heavy metal silicate by the following reaction. M ²⁺ + Na ₂ SiO ₂ → MSiO ₂ + 2Na ⁺ (2) As a result, the heavy metal contained is taken in and insolubilized. Then, the slaked lime and sodium silicate further react as in the following formula to produce calcium silicate. Ca (OH) ₂ + Na ₂ SiO ₂ → CaSiO ₂ + 2NaOH (3) Since the calcium silicate produced by this is an extremely porous substance, it has a large surface area and is excellent in adsorptivity, and adsorbs unreacted heavy metals and the like. It prevents the elution, and the heavy metal silicate forms a matrix structure, and the heavy metal ions inside are considered to be inactivated by being surrounded by oxygen. Due to these synergistic effects, the heavy metals are firmly fixed. Will be done. When the industrial waste contains oil, it is adsorbed by the generated porous calcium silicate. This is considered to be the same principle that moisture in the air is adsorbed by silica gel which is a desiccant and odor of a refrigerator or the like is adsorbed by activated carbon which is a deodorant. Further, since the oil content forms calcium silicate in the portion where the oil content exists, the oil content is adsorbed in a very thin film form, and the calcium silicate has an extremely large holding force for adsorbing the oil content. If the industrial waste is an aqueous solution, the calcium silicate and the heavy metal silicate will precipitate and can be recovered. If the industrial waste is a mud, it will be disposed of in the mixed state as it is. .. The silicon, which is added as necessary, combines with the oxygen contained therein to form silicic acid, which urges the function of the sodium silicate, and magnesium oxide (preferably magnesium) promotes the temperature raising effect.

[0006]

EXAMPLES Next, specific examples of the present invention will be described to provide an understanding of the present invention. First, as the treating agent, sodium silicate of 3 to 20% by weight (preferably 5 to 8% by weight) and 0.5 to 5% by weight (preferably 2 to 3% by weight) are added to 100% by weight of quicklime. %) And 3 to 15% by weight of silicon
(Preferably 4 to 7% by weight), and a small amount of non-volatile, saturated oil is added so that the quicklime powder is wrapped in an oil film. As a result, even if it is stored for a long time, quicklime contained therein is prevented from reacting with the moisture in the air.

In this example, the industrial waste used in the experiment was a sludge-like industrial waste containing an oil component, tetrachloroethylene, cadmium, hexavalent chromium, total mercury, lead and the like. The industrial waste is put into a mixer driven by a motor, the treating agent is added in an amount substantially equal to the amount of the industrial waste, and water necessary for the quicklime to react is added. As a result, the reaction (1) occurs, and the overall temperature rises to about 100 to 180 ° C.

During the above stirring process, the reactions (2) and (3) also occur, so that volatile oils (for example, thinner oil, ethyl acetate, toluene) among the oil components contained inside. Is gasified and volatilized from the sludge. Further, the non-volatile oil component contained in the sludge becomes a thin film and adheres to the periphery of the porous calcium silicate, and in some cases is decomposed by heat. Table 1 shows the components of the industrial waste treated by the above method before and after the treatment.

[0009]

[Table 1]

As is clear from Table 1, after the treatment, the oil content was reduced to 10% or less, tetrachloroethylene and cadmium were not detected, and hexavalent chromium, total mercury and lead were extremely reduced. Therefore, the treatment agent can render the industrial waste harmless.

Although the above-mentioned embodiment is directed to sludge-like substances, the present invention can be applied to liquid industrial waste such as plating waste liquid. In this case, water injection is unnecessary and the treatment agent is not used. By adding and stirring, quick lime causes an exothermic reaction, and the temperature is set to 70 to 100 ° C. to accelerate the reaction. The calcium silicate and heavy metal silicate produced by the reaction can be recovered as a precipitate.

[0012]

According to the agent for treating industrial waste containing heavy metals and the like according to claim 1 and the method for treating industrial waste containing heavy metals and the like according to claim 2, quick lime contained in the treating agent is subjected to an oil film treatment. Therefore, even if it is exposed to the air for a long period of time, the slaked lime does not react with water, and a long life can be maintained. Then, after the treating agent is added, an exothermic reaction is caused by the contained quick lime to promote the reaction between the heavy metal and the sodium silicate, and the heavy metal and the like can be fixed, and at the same time, the oil content and the like contained by the calcium silicate generated Are adhered and oil is removed at the same time, and as a result, elution of heavy metals and the like from the treated product can be prevented.

Claims (2)

[Claims] 1. The external content is 3 to 100% by weight of quicklime.
20% by weight of sodium silicate and, if necessary, 0.5 to 5% by weight of magnesium oxide and 3 to 15% by weight of silicon are mixed, and at least the quicklime is subjected to an oil film treatment. A treatment agent for industrial waste containing. 2. Quick lime 1 is added to industrial waste containing heavy metals and the like.
An appropriate amount of a treating agent obtained by mixing 3 to 20% by weight of sodium silicate with 0.5% to 5% by weight of magnesium oxide and 3 to 15% by weight of silicon with respect to 00% by weight is mixed, When the industrial waste does not contain water, water necessary for the quicklime to react is added and stirred, and the quicklime is heated to raise the temperature of the mixture to accelerate the reaction, thereby removing the heavy metal and the like. A method for treating industrial waste containing heavy metals, which is characterized by being insolubilized.