Method for treating fly ash with high salinity and high heavy metal content
A treatment method and heavy metal technology, applied in the direction of alkali metal chloride, process efficiency improvement, etc., can solve the problems of high cost of fly ash treatment, large energy consumption, low water solubility, etc.
Active Publication Date: 2018-06-19
深圳市小荷环保技术有限公司
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Problems solved by technology
Although dioxin is highly toxic, its content in fly ash is very small, and its water solubility is extremely low, so it is relatively easy to control its migration
However, since this process consumes a lot of energy, and requires strict follow-up flue gas treatment for volatile heavy metal elements such as Pb, Cd, and Zn, the cost of fly ash treatment is relatively high. Currently, it can only be used in economically developed countries.
[0004] In addition, there is no report on a cost-effective method to treat soluble salts and high-content heavy metals in fly ash at the same time in China, how to separate heavy metals and chloride salts in fly ash, and realize the harmlessness of fly ash and the separation of heavy metals and salts. Resource recovery is an important research topic
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[0015] The present invention will be described in further detail below in conjunction with accompanying drawing:
[0016] see figure 1 As shown, the fly ash treatment method with high salt and heavy metal content, its process steps:
[0017] (1) Wash the fly ash once with dilute hydrochloric acid with a concentration of 0.5mol / L and a liquid-solid ratio of 3:1, so that the soluble salt in the fly ash enters the washing water, and after filtration and separation, the washed fly ash and concentrated brine, concentrated brine The medium salt content is between 10% and 20%, which meets the content requirements of reverse osmosis and evaporation crystallization.
[0018] (2) After washing the fly ash, use concentrated hydrochloric acid with a concentration of 3mol / L and a liquid-solid ratio of 4:1 for acid leaching, so that the heavy metals in the fly ash enter the leaching solution to obtain a heavy metal leaching solution. The main heavy metal concentrations in the leaching solu...
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The present invention relates to a method for treating fly ash with high salinity and high heavy metal content. According to the method, fly ash is washed by using an acid washing liquid. Soluble saltin the fly ash is transferred to the washing liquid to the utmost extent by controlling a liquid-solid ratio, thereby obtaining a strong brine worthy of recovery value, and the obtained strong brineis separated for recovery of salt and then returned to the process to be used as a replenishing liquid for continuously washing next batch of fly ash. An acid leaching liquid is employed for acid leaching. Heavy metals in fly ash are transferred to leachate to the utmost extent by controlling a liquid-solid ratio, thereby obtaining a heavy metal leachate worthy of recovery. After the separation and recovery of heavy metals, the residual liquid is used as a leaching replenishing liquid for leaching next batch of fly ash. The acid-leached fly ash is subject to a stepwise washing process to remove residual heavy metal ions and heavy metals which are not leached completely, so that the leaching toxicity of the fly ash can reach the standard and harmless fly ash can be obtained. The method fortreating fly ash provided in the present invention is low in cost and good in treatment effect, and can achieve harmless treatment of fly ash and recycling of heavy metals and soluble salt simultaneously.
Description
technical field [0001] The invention relates to the technical field of solid waste treatment, in particular to a new fly ash treatment method for treating waste incineration fly ash by using a hydrometallurgical process. Background technique [0002] Domestic waste incineration fly ash in my country has the characteristics of huge production, enrichment of heavy metals and dioxins, and high content of volatile elements. The risk of fly ash mainly comes from the heavy metals and dioxins enriched in it. Although dioxin is highly toxic, its content in fly ash is very small, and its water solubility is extremely low, so it is relatively easy to control its migration. Dioxins can be completely decomposed by controlling the temperature in the incinerator to be greater than 850°C and controlling the flue gas to stay in the furnace for more than 2 seconds. The content of heavy metals in fly ash is relatively high, and they are easily dissolved and released in water, which is the t...
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IPC IPC(8): C22B7/02C01D3/04
CPCC01D3/04C22B7/007C22B7/02Y02P10/20
Inventor 谢巧玲林涛王丹丹陈福明张淑然
Owner 深圳市小荷环保技术有限公司