TWI789600B - Method for enhancing stabilization and detoxification of thermal treatment facilities collected powder - Google Patents

Abstract

In the air pollution control devices (APCDs) of theraml treatment facilities, powders collected from APCDs often contain hazardous substances such as heavy metals, dioxins (DXN), and polycyclic aromatic hydrocarbons (PAHs), which are hazardous industrial waste and cannot be reused. Since the properties of such powders are still different, therefore, this invention provides a purposeful and stepwise method, which promotes stabilization and detoxification of powders using one or two steps. The first step is a short term of water elution treatment and/or adding high-concentration acid solution (such as sulfuric acid and hydrochloric acid) to adjust the pH value of the slurry to stabilize the heavy metals; thereafter, powder reuse detection is carried out. Reusable powder is confirmed if pass the detection; otherwise, thermal treatment is performed to remove organic hazardous substances such as dioxin, PAHs, etc., and finally achieve the detoxification and reusable purposes.

Description

A method to promote the stabilization and harmlessness of dust-collected powder in heat treatment facilities

The present invention is related to the technical field of stabilization and detoxification of dust-collecting powder containing harmful heavy metals and/or harmful organic pollutants produced by heat treatment facilities. The harmless method, through the step-by-step processing and judgment steps, removes or reduces the harmful substances in the dust collection powder to the reuse standard, which is conducive to subsequent reuse of raw materials.

Dust collection equipment (such as cyclone dust collection dust collector, electrostatic precipitator, washing tower, bag filter, etc.) often contain harmful substances such as heavy metals, dioxins (DXN), polycyclic aromatic hydrocarbons (PAHs), and are often harmful substances after testing waste and cannot be reused. Due to the differences in the properties of such dust-collecting powders, for example, some are mainly composed of inorganic heavy metals, some are mainly composed of organic dioxins, some are mainly composed of organic polycyclic aromatic hydrocarbons, or some are composed of both. aforementioned Hazardous substances, so it is not easy to have a simpler method of stabilization and harmlessness. Therefore, most of the methods currently on the market to deal with such harmful dust-collecting powders are solidified with cement, and then the solidified matter is buried for disposal. However, solidification not only increases the volume of powder waste, but also the solidified material is placed in a landfill for a long time, and harmful substances may be dissolved out during rainfall, causing soil, surface water, or groundwater pollution.

Known technologies for processing powders or substances after high-temperature treatment, such as the following ROC invention or new patents or publications:

Invention No. 301697 "stabilization and reuse of ashes"; Invention No. 468021 "ash melting method and ash melting furnace"; Method and device for removing chloride contained in bottom ash"; No. I314543 "Method for making coal ash into adsorption material"; No. I328095 "Method for reusing incinerator fly ash"; No. I325795 "Using dicalcium phosphate Method for Stabilizing Hydrate Powder in Incinerator Bottom Slag of Heavy Metals and Odor Control"; No. I310699 "Method and Device for Decomposing Dioxin"; No. I288028 "Washing Procedure of Incineration Bottom Slag"; No. I257330 "Treatment Method of Incineration Fly Ash and device"; No. I231234 "Treatment agent and procedure for dioxin compounds discharged from incinerators"; Invention Publication No. 523550 "A chain steel method for recycling waste incineration fly ash by electric arc furnace"; No. M369800 "Fly ash Chelating agent mixing and adding equipment" and other patents and publications.

The differences between the preceding disclosure and the present invention are further described. It can be seen from the above-mentioned related processing methods that most of the technologies are water washing, gasification, aeration, high Its mechanism is to decompose or convert solid-phase harmful substances containing heavy metals into liquid or gas phases by washing or high temperature, or to melt inorganic substances by high temperature and then coat ash to make it difficult to dissolve.

The main treatment technology in this case is to first use water to elute and separate the dust collection powder, that is, to remove the harmful heavy metals from the dust collection powder into a waste liquid (the waste liquid needs to be treated separately), and add acid (or re-stabilize agent) stabilization treatment. Afterwards, the powder is inspected, and if it meets the raw material standards for reuse, it can be reused. On the contrary, high-temperature heat treatment can remove or reduce harmful substances such as dioxins and polycyclic aromatic hydrocarbons through the mechanism of high-temperature destruction and decomposition of organic matter, so as to meet the raw material standards for reuse.

The main purpose of the present invention is to provide a method for promoting the stabilization and harmlessness of dust collection powder in heat treatment facilities, so as to achieve the reuse purposes of "stabilization", "harmlessness" and "materialization". The reason is that, in order to achieve the aforementioned purpose, the stabilization and harmlessness of the present invention include the following steps:

Feed the dust-collecting powder and water in a specific ratio, that is, pour the water into the pre-mixing tank first, and adjust the motor to drive the water to generate vortex and disturbance, and then put the dust-collecting powder into the pre-mixing tank for sufficient mixing .

The slurry (slurry) in the aforementioned premixing tank is transported to the elutriation tank for one or two steps of elution treatment, including elutriation of the slurry with a stirrer that can control the rotation speed, and centrifugal (or Press filter) for solid-liquid separation of slurry.

In the washing process of the above-mentioned one or two steps, high-concentration acid solution (such as sulfuric acid or hydrochloric acid, etc.) is added to control the pH value of the slurry, so as to facilitate the formation of heavy metal precipitates from the heavy metals contained in the original powder and achieve stabilization. What's more, inorganic heavy metal stabilizers can also be added to enhance the stabilization effect.

After the solid-liquid separation, the physical and chemical properties of the powder are tested. If it meets the reuse standard, it becomes a harmless and reusable powder.

On the contrary, high-temperature heat treatment is carried out to remove organic harmful substances such as dioxins and polycyclic aromatic hydrocarbons.

After the heat treatment, the physical and chemical properties of the powder are tested. If the reuse standard is met, it becomes a harmless and reusable powder; otherwise, it returns to the stabilization treatment procedure.

The method of the present invention is suitable for the dust collection powder of heat treatment facilities with different properties, and the main purpose is to reuse the powder; in addition, the method of the present invention is step-by-step, and after meeting the reuse standard, it becomes a harmless recycled powder body, to achieve the purpose of simplifying the processing steps and saving energy and reducing carbon.

100: incineration powder

110: pre-stirred mix

120: One or two step elution treatment

130: Stabilization treatment

140: Harmless reuse powder

150: heat treatment

Fig. 1 is a flow chart of a preferred embodiment of the present invention.

Referring to Figure 1, a preferred embodiment of the present invention includes the following steps:

100 is the dust collection powder ready for the heat treatment facility to be treated.

Inject a specific amount of water (liquid-solid ratio between 1.5-6.0) into the 110 pre-mixing tank, turn on the motor to form a turbulent vortex in the water body in the pre-mixing tank, and gradually pour in the dust collection powder for pre-mixing and mixing.

The slurry (slurry) in the aforementioned premixing tank is transported to the elutriation tank, and the elution treatment of 120 or two steps is carried out, including the stirring of the slurry with a controllable rotation speed (the rotation speed is between 100-600rpm). Elutriation, and the solid-liquid separation of the slurry by centrifugal (or press filter).

In the washing process of the above-mentioned one or two steps, add high-concentration acid solution (such as sulfuric acid, or hydrochloric acid, etc.) to control the pH value of the slurry (between 9.0-12.0), so as to facilitate the formation of heavy metal precipitates from the heavy metals contained in the original powder , performing 130 stabilization treatments.

What's more, inorganic heavy metal stabilizers, such as sulfur-based and phosphoric acid-based stabilizers, can be added to enhance the stabilization effect.

After the solid-liquid separation, the physical and chemical properties of the powder are tested. If it meets the reuse standard, it becomes 140 harmless reuse powder.

On the contrary, high temperature 150°C heat treatment is carried out, and the temperature is controlled between 800-950°C to remove organic harmful substances such as dioxins and polycyclic aromatic hydrocarbons.

After the heat treatment, the physical and chemical properties of the powder are tested. If it meets the reuse standard, it becomes 140 harmless reuse powder; otherwise, it returns to 130 stabilization treatment.

100: Dust collection powder

110: pre-stirred mix

120: One or two step elution treatment

130: Stabilization treatment

140: Harmless reuse powder

150: heat treatment

Claims (1)

A method for promoting the stabilization and harmlessness of dust collection powder in heat treatment facilities, the steps are as follows: prepare the powder collected by the dust collection equipment of the heat treatment facility to be treated; inject a specific amount of water (the amount of water and the quality of the powder) into the pre-mixing tank The liquid-solid ratio is between 1.5-6.0), turn on the motor to form a turbulent vortex in the water body in the pre-mixing tank, and gradually pour the dust collection powder into it for pre-mixing; transport the slurry in the pre-mixing tank to the elutriation tank Among them, one or two steps of elution treatment are carried out, including elutriation of the slurry with a stirrer (rotating speed between 100-600rpm), and solid-liquid separation of the slurry with a centrifugal (or filter press); washing During the panning process, add sulfuric acid, hydrochloric acid, or a combination of these to control the pH value of the slurry (between 9.0-12.0), so that the heavy metals in the powder can form precipitates and stabilize them; what’s more, sulfur can be added Phosphate-based, phosphoric acid-based stabilizers, or a combination of these; the physical and chemical properties of the powder after solid-liquid separation are tested, and if it meets the reuse standard, it becomes a harmless recycled powder; otherwise, heat treatment (temperature between 800-950°C) to remove organic harmful substances such as dioxins and polycyclic aromatic hydrocarbons; and to test the physical and chemical properties of the powder after heat treatment. If it meets the reuse standard, it will become a harmless reuse powder; otherwise , returns to the stabilization process.

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