TWI745018B - Method of processing mswi fly ash with multiple washing operations - Google Patents

Abstract

A method of processing MSWI fly ash with multiple washing operations includes a preparation step, an initial washing step, an initial dehydration step, a refining washing step, and a refining dehydration step. The preparation step is to prepare MSWI fly ash, clear water and reclaimed water. The initial washing step is to stir the MSWI fly ash and the reclaimed water together for washing the MSWI fly ash, and dehydrate the MSWI fly ash in the initial dehydration step to thereby obtain initial-washed MSWI fly ash and waste water. The refining washing step is to stir the initial-washed MSWI fly ash and the clear water together for washing the initial-washed MSWI fly ash, and dehydrate the initial-washed MSWI fly ash to obtain reclaimed MSWI fly ash and reclaimed water. Thus, the reclaimed water can be used in the initial washing step to thereby reduce waste of water resources. Chloride contained in the reclaimed MSWI fly wash can be reduced effectively, and the reclaimed MSWI fly wash can be reused to thereby reduce costs for water washing and increase the washing efficiency.

Description

Multi-stage scrubbing incineration fly ash treatment method

The present invention relates to a treatment method of incineration fly ash, in particular to a treatment method of multi-stage scrubbing incineration fly ash.

In the process of incineration of general waste, the incineration fly ash produced is collected in the flue gas pipeline, flue gas purification, separator and dust collector device, etc. The powder material has a lighter bulk density and a small particle size, and its composition is complex. Very toxic: fly ash not only contains a large amount of heavy metal inorganic harmful substances such as Cd, Cr, Cu, Ni, Pb and Zn, but also contains a high concentration of organic carcinogens such as dioxins with the strongest toxicity, which is designated by the state Hazardous wastes, therefore, must be stabilized or treated in a harmless manner before they can be reused or finally disposed of. The existing incineration fly ash is mostly solidified and stabilized for intermediate treatment, while the solidification method is based on curing agents (such as cement). , Sodium silicate, lime or clay, etc.) are added to the incineration fly ash to form a solid lumpy substance, which makes the harmful substances difficult to dissolve. Although the solidification treatment has the advantages of simple operation, low installation cost, no waste gas and wastewater treatment problems, but After curing, the volume and weight will increase, and the curing agent and natural resources will be wasted. The burial treatment must be divided into sections to reduce the burial period. At the same time, the incineration fly ash contains high concentration of chloride salts, which affects the durability of the solidified body, and heavy metals can still be stored for a long time. Melt out doubts.

In addition, the soluble substances in fly ash from waste incineration plants mainly include potassium, sodium, chloride ions, etc., accounting for about 20% of the fly ash. After the chlorine salt is removed, it can be made into industrial secondary potassium and sodium salt. Insoluble substances mainly include Calcium, silicon, aluminum, iron, etc., account for about 80% of the fly ash. Its composition is close to high-quality limestone. It can be used as a cement raw material to produce cement clinker. However, due to the volatile chloride salt in the fly ash, it is used in cement kilns. During the sintering process, cement kiln corrosion and skinning will be caused. Therefore, whether the fly ash is to be processed into industrial secondary potassium or sodium salt or used as a raw material for the production of cement clinker, the fly ash must be removed first In the chlorine salt.

The existing method mainly uses water washing to remove most of the chloride salt, but currently uses 2 to 8 times the weight ratio of water to mix fly ash, stir and scrub the solid-liquid separation, so that part of the heavy metals and chloride salts are taken away by the water , And reduce the heavy metals and chloride salts remaining in the fly ash; however, the general scrubbing is mainly a one-time scrub, and clean water is used for scrubbing each time. When the heavy metals or chloride salts in the fly ash after scrubbing are more demanding When it is high, it is more necessary to use higher multiples of water for mixing. In addition to consuming a lot of water resources, and using clean water alone to use one-time scrubbing, it cannot be effectively scrubbed. The large amount of waste water produced can also easily cause water resources. The waste must be improved.

Therefore, the object of the present invention is to provide a multi-stage scrubbing and incineration fly ash treatment method, which can reduce the waste of water resources, and at the same time can effectively reduce the chlorine salt content in the recovered fly ash, so that the recovered fly ash Can be used again.

Therefore, the multi-stage scrubbing and incineration fly ash treatment method of the present invention includes a preparation step, an initial washing step, an initial removal step, a fine washing step, and a fine removal step; wherein the preparation step prepares the incineration fly ash to be treated, And a clean water and a recycled water. In the initial washing step, the recycled water is mixed with the incineration fly ash, and then stirred and scrubbed, so that part of the heavy metals and chloride salts in the incineration fly ash are taken away by the recycled water. Then through the initial removal step, dehydration treatment is carried out to separate the recovered water from the incineration fly ash, so that the recovered water will form wastewater with a higher solubility, and the incineration fly ash will form a lower content of heavy metals and chloride salts. The first-washed fly ash is then passed through the fine washing step, the first-washed fly ash and clean water are stirred and scrubbed, and then subjected to the fine removal step to obtain recycled water and recycled fly ash, respectively. Therefore, the recycled water system provides the The use in the initial washing step can effectively reduce the waste of water resources, and at the same time can effectively reduce the chloride salt component in the recovered fly ash, so that the recovered fly ash can be reused again.

The foregoing and other technical contents, features, and effects of the present invention will be clearly understood in the following detailed description of the preferred embodiment with reference to the drawings.

Referring to Fig. 1, the first preferred embodiment of the present invention. The incineration fly ash treatment method of the present invention includes a preparation step of preparing incineration fly ash, clean water and recovered water, and a preliminary washing by mixing the incineration fly ash and the recovered water for scrubbing Steps: a step of removing the incineration fly ash and the recovered water from the preliminary washing step by pressure filtration; In the washing step, the first washing fly ash is separated from the clean water by pressure filtration; the incineration fly ash can be collected from the air pollution control equipment of the garbage incineration plant, and the clean water can be tap water, distilled water or soft water treatment The recovered water is the water obtained after scrubbing the incineration fly ash and then separating the incineration fly ash by pressure filtration.

Continuing the foregoing, the initial washing step is to stir the incineration fly ash and the recovered water, and the incineration fly ash: the recovered water is mixed in a weight ratio of 1:2-5 and then stirred and scrubbed. In the best condition, it is The incineration fly ash: the weight ratio of recycled water is 1:3. For example, when 100 kilograms of incineration fly ash is mixed with at least 300 kilograms of recycled water, the mixing time is adjusted according to the size of the equipment used and the scrubbing state. After the incineration fly ash and the recovered water are evenly stirred, since the incineration fly ash contains a higher concentration of chloride salts, when the incineration fly ash and the recovered water are input into a first filter press and dehydration device, the first After the filter press and dehydration equipment, the wastewater with higher chloride salt concentration and the initial washing fly ash with lower chloride salt concentration will be produced after the filter press. The wastewater can be fed into a waste water tank for subsequent treatment. The washed fly ash can be press filtered to at least the moisture content below 38%, so as to facilitate subsequent processing.

As mentioned above, the fine washing step is to mix the first-washed fly ash with the lower chlorine salt content, and then mix it with a clean water. The first-washed fly ash: clean water is mixed in a weight ratio of 1:2-5, and the best In this situation, it is the initial washing fly ash: the weight ratio of the recycled water is 1:3, that is, if 100 kg of the first washing fly ash is used, 300 kg of clean water is used for mixing, which can be based on the size of the equipment used and the scrubbing. Adjust the mixing time to make the first clean fly ash and the clean water evenly stirred, because the first clean fly ash contains less chloride salt, so when the fine removal step is input for the first clean fly ash in the previous stage When the second filter press dehydration equipment performs filter press dehydration, it will produce recycled water with a lower content of chloride salts and recycled fly ash with a very low content of chloride salts. The recycled water can be used for the initial washing step, and the recovery The chlorine salt contained in the fly ash component is less than 2% by weight, and it can be used as a follow-up treatment to industrial di-potassium and sodium salt, even when the recycled fly ash contains less than 1% by weight of the chloride salt It can also be used as a cement raw material to produce cement clinker, etc., so that the recovered fly ash can be reused.

Therefore, the present invention uses the incineration fly ash to wash with the recovered water at a weight ratio of 1:3 weight ratio, the first washed fly ash obtained from dehydration is then washed with water at a weight ratio of 1:3, and then the values obtained after pressure filtration As follows (weight percentage): category Original chlorine content Chlorine content after fine washing Incineration of fly ash 1 20.38% 0.67% Incineration of fly ash 2 17.72% 0.48% Incineration of fly ash 3 18.9% 0.5% Incineration of fly ash 4 18.63% 0.82% Incineration of fly ash 5 19.02% 0.99% Incineration of fly ash 6 20.1% 0.97% Incineration of fly ash 7 20.42% 0.76% average 19.31% 0.74%

As mentioned above, after the initial washing step and the fine washing step and the use of recycled water and clean water, the two scrubbing only consumes 3 times the relative weight of the incineration fly ash, and the incineration fly ash can be used. The content of chloride salt is reduced to less than 1%.

Therefore, the present invention divides the incineration fly ash into multiple scrubbing at least the initial washing step and the fine washing step, that is, the recovered water generated in the fine washing step is used as the incineration fly ash containing higher chloride salt content in the preliminary washing step. When the incineration fly ash is scrubbed in the initial washing step, it will produce the initial washing fly ash with a lower chlorine salt content, and then use clean water to scrub the initial washing fly ash, so that the recycled water is used for scrubbing The incineration fly ash with a higher concentration of chloride salt will then form the initial washing fly ash with a lower content of chloride salt, and then use clean water for scrubbing, which can effectively reduce the waste of water resources and at the same time ensure that the incineration fly ash is scrubbed after scrubbing. Quality, achieve the effect of reducing washing cost and improving washing efficiency.

Referring to Fig. 2, the second preferred embodiment of the multi-stage scrubbing incineration fly ash processing method of the present invention, this embodiment still includes a preparation step, a preliminary washing step, a preliminary removal step, a fine washing step, a fine removal step, etc., The effects to be achieved by the foregoing steps are the same as those in the first embodiment, and will not be described in detail. In particular, in this embodiment, at least one washing step and at least one washing step are sequentially added between the initial removal step and the fine washing step. In this washing step, the recovered water obtained after the fine washing is used for scrubbing, and the weight ratio of the first washing fly ash to the recovered water in this washing step is 1:2-5, and the best ratio is The ratio of the primary washing fly ash and the recovered water is 1:3; in addition, the secondary desorption step is to generate recovered water and secondary washing fly ash from the press filter, so as to provide the recovered water for use in the primary washing step, and the resultant The secondary washing fly ash is processed in the next stage of secondary washing step or fine washing step; therefore, through the design of this secondary washing step and secondary removal step, the chlorine salt contained in the recovered fly ash after the fine removal step can be used. Condition, adjust whether to add this washing step and this degassing step, and then carry out graded cleaning in order, and the recovered water generated after each dehydration will be used for the scrubbing in the previous step, so as to achieve thick water washing and thick ash. The concept of washing the ash with clean water realizes the efficient utilization of water, so that the cleanest recycled fly ash can be scrubbed with the least water, so as to reduce the washing cost and improve the washing efficiency.

In summary, the multi-stage scrubbing and incineration fly ash treatment method of the present invention includes a preparation step, a preliminary washing step, a preliminary removal step, a fine washing step, and a fine removal step. It is used for one-step scrubbing, and waste water is only produced after the initial removal step. The concentration of the waste water will be more concentrated, which can effectively reduce the waste of water resources, and at the same time can effectively reduce the chlorine salt in the recycled fly ash. The components enable the recovered fly ash to be reused again, achieving the effect of reducing washing costs and improving washing efficiency.

However, what has been described above is only to illustrate the preferred embodiments of the present invention, and should not be used to limit the scope of implementation of the present invention, that is, simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the content of the description of the invention. , Should still fall within the scope of the invention patent.

without

Fig. 1 is a flow block diagram of the first embodiment of the present invention. Figure 2 is a flow block diagram of the second embodiment of the present invention

Claims (8)

A multi-stage scrubbing incineration fly ash processing method, which includes: a preparation step, which prepares incineration fly ash to be processed, and a clean water and a recycled water; a preliminary washing step, which performs the incineration fly ash and the recycled water Stirring and scrubbing; the initial removal step, the aforementioned agitation is input to a first filter press dehydration device to separate the incineration fly ash and the recovered water to obtain a waste water and the initial washing fly ash; Wash the fly ash and clean water for stirring and scrubbing; and in the fine removal step, the aforesaid stirring is input into a second filter press dehydration device to separate the fly ash and water to obtain a recycled water and recycled fly ash, respectively. The water system is used in the initial washing step, and the recovered fly ash is used for subsequent processing. The method for processing multi-stage scrubbing incineration fly ash according to claim 1, wherein the weight ratio of the incineration fly ash to the recovered water in the initial washing step is 1:2-5. The method for processing multi-stage scrubbing and incineration fly ash according to claim 1, wherein the weight ratio of the first washing fly ash to the clean water in the fine washing step is 1:2-5. According to the method for processing multi-stage scrubbing incineration fly ash according to claim 1, wherein, the moisture content of the preliminary washing fly ash is within 38% in the preliminary removal step. According to the multi-stage scrubbing and incineration fly ash processing method of claim 1, wherein the chlorine salt in the recycled fly ash component needs to be less than 2%. According to claim 3, the multi-stage scrubbing and incineration fly ash processing method, wherein, when the recycled fly ash component accounts for more than 2% of the chloride salt, the recycled fly ash will be sent to the fine washing step for processing. The processing method for multi-stage scrubbing and incineration fly ash according to claim 1, wherein at least one washing step and at least one removing step are sequentially added between the initial removal step and the fine washing step, wherein the second washing step will The recovered water obtained after the fine removal is used for scrubbing, and the second removal step is to generate recycled water and secondary washing fly ash from the press filter, so as to provide the recovered water for use in the primary washing step, and the resulting secondary washing The fly ash is processed in the next washing step or fine washing step. The method for processing multi-stage scrubbing and incineration fly ash according to claim 1, wherein the weight ratio of the first washing fly ash to the recovered water in the second washing step is 1:2-5.

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