A method for stabilizing construction waste contaminated with various heavy metals

Abstract

The present invention relates to a method for stabilizing construction waste polluted by various heavy metals. Firstly dry and crush the construction waste polluted by heavy metals, then pickle with citric acid to dissolve the heavy metals on the surface of the construction waste, separate the solid and liquid after 23-25 ​​hours, obtain the eluent and solid, and recycle and treat the heavy metals in the eluent to meet the discharge standards; Add a heavy metal curing agent to the solid, add water to adjust and stabilize, stir or shake for 24 hours, then separate after standing for a week to obtain the supernatant and pickling-stabilized construction waste, and the supernatant returns to the pickling process; The washed-stabilized construction waste was tested for leaching toxicity according to the HJ / T299-2007 method, and the results showed that it complied with the first-class national standard for comprehensive sewage discharge. The process steps of the invention are simple, the waste liquid is recycled after being treated, the medicament used is safe and environment-friendly, has obvious stabilizing effects on heavy metals, and ensures the environmental safety in landfilling or resource utilization of construction waste polluted by heavy metals.

Description

technical field [0001] The present invention relates to a method for stabilizing construction waste contaminated with various heavy metals. The invention belongs to the technical field of heavy metal treatment in construction waste. Background technique [0002] With the rapid development of my country's economy and the rapid progress of urbanization, a large amount of construction waste is generated by demolition, reconstruction and expansion projects and new construction projects. Contaminated construction waste from demolition or remodeling. For example, the construction waste taken from the electroplating workshop of an electroplating factory in Shenzhen contaminated by heavy metals has a zinc content of 2885 mg / kg, a copper content of 47553 mg / kg, and a chromium content of 7095 mg / kg. This type of construction waste contaminated by heavy metals, if not properly disposed of, will have a serious impact on the surrounding soil, surface and groundwater and other environmen...

AI Technical Summary

Problems solved by technology

If this kind of construction waste polluted by heavy metals is not properly treated, random stacking will have a serious impact on the surrounding soil, surface and groundwater and other environments. Under the washing of acid rain and heavy rainfall, construction waste polluted by heavy metals will The release of various heavy metals in the environment leads to long-term environmental risks

[0003] In recent years, there have been a lot of studies on heavy metal pollution control at home and abroad, among which the treatment and stabilization methods of heavy metals in soil and ash, such as "A Treatment Method for Heavy Metal Cd Contaminated Soil" (application number CN201210374993.X, publication number CN102886375A ), using electric restoration + permeable reaction wall to realize the enrichment and removal of heavy metals in the soil; "A Method for Chemically Stabilizing Municipal Waste Incineration Fly Ash" (application number 200610007581.7, publication number CN1810395A) uses a silicate chemical stabilizer Stabilize municipal waste incineration fly ash so that its leaching toxicity is lower than the identification standard of hazardous waste; however, it is not suitable for the treatment and stabilization of construction waste subject to heavy metals

However, there is very little research on the treatment method of construction waste polluted by heavy metals. In the relevant literature and patent "A Treatment Method for Construction Waste Contaminated by Chromium" (Application No. 201210116994.4, Application Publication No. CN102652953A), the construction waste containing chromium is first washed with clear water, After dehydration, use 0.1-0.2mol / L citric acid to clean the chromium-contaminated construction waste, the removal rate is over 95%, and the total chromium in the leaching toxicity test is less than 1.5mg / L

This method is only aimed at the treatment of construction waste contaminated by chromium, without accounting for the amount of citric acid and the total amount of heavy metals in construction waste, and has high requirements for the crushing of construction waste. ) consumes a lot of energy, and at the same time, the smaller particle size limits the subsequent use of construction waste. If the cleaned construction waste is directly landfilled, there is still a certain environmental risk. In addition, no other heavy metals such as zinc and copper have been detected. Relevant reports on the treatment and stabilization methods of construction waste polluted by various heavy metals such as , lead, etc.

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