Three different types of sludge were produced in the production process of a chemical company in Jiangsu and Zhejiang, and were treated with three different dewatering equipments. The final average moisture content of the dehydrated sludge was about 70%, and the heat pump low temperature drying technology was used to treat them separately, and finally achieved stability. Disposal in different directions of harmlessness and resource recovery achieves the goal of harmlessness, while generating additional benefits.

Most components of chemical sludge are complex and contain toxins and heavy metals. Improper treatment can cause serious pollution and harm to the environment. Sludge is prone to breed pathogens, parasites and eggs. Heavy metals and organic compounds are difficult to degrade. The animals and plants in the polluted area accumulate, and the soil damaged by the pollution is difficult to repair.

At present, the traditional sludge treatment technologies at home and abroad mainly include landfill, incineration and composting. Landfill and composting methods have high requirements on sludge and a small receiving range; incineration easily produces dioxins with strong carcinogenic effects, and the cost of incineration is high, and the burden on enterprises is heavy. After actual verification, the sludge is subjected to low-temperature drying by heat pump for front-end treatment, which can not only significantly reduce the amount of sludge disposal, reduce the cost of later disposal, but also retain the components in the sludge, reduce secondary pollution, increase resource utilization, The method of sludge disposal is broadened.

One of the company's sludges contains chromium, cadmium, nickel and other heavy metals, one contains carbon, the other contains organic ketones and other components, and the accumulation is prone to spontaneous combustion; the three sludges form 70% after dehydration The wet mud with a water content of 6-7 tons per day is mostly treated as hazardous solid waste, which is expensive. According to the difference of sludge composition, it is planned to use different treatment methods for the three kinds of sludge to achieve resource, stabilization and harmless treatment. We are specially invited to provide solutions and equipment to reduce the amount of heat treatment by heat pump drying After that, the moisture content of dry mud is 20 ~ 30%, and the reduction is 60%.

一. Sludge treatment principle

Different sludge components and different disposal methods can achieve different purposes. The customer formulates the principle of classification and disposal from the point of reducing hazards and increasing benefits, opening the source to simplify the process and operation.

The sludge reduction after dewatering adopts the same process and is carried out in batches, which not only simplifies the process, but also saves investment, compares various drying processes, and finally determines to use a heat pump low temperature drying process.

二. Project site survey

In the dewatering process, the customer uses three different dewatering machines to process the three kinds of sludge separately. In order to avoid mixing, each set up a separate outlet, which is achieved by the same set of equipment at the stage of sludge drying and weight reduction. According to this idea, first of all, the problem of receiving three materials and finally delivering them to the dryer is solved.

Two of the three dewatering machines on the site use a plate and frame filter press, and one uses a stacked screw dewatering machine. It is installed in the dehydration workshop on the second floor. Mud discharge hopper, each discharge port is arranged near. The three dehydration equipments operate independently, and there is a possibility that the blanking time overlaps.

三. Scheme design

Receiving the three types of sludge, according to the amount of feeding and the period of feeding, considering the processing time of the dryer, choose a buffer tank with a suitable volume, each equipped with a wet sludge conveyor, which is sent to a common set of transfer mixing silo After treatment, it is lifted to feed the dryer, and the dry mud is output and bagged.The total dewatering capacity of the project is more than 4 tons per day. 

The heat pump low-temperature drying model with a dewatering capacity of 4800 is selected, and the daily sludge production is less than 3 tons. The three types of mud use the same low-temperature drying, the type switching is fast, and the operation is automated, which fully meets the customer's plan and expected results.

四. Conclusion

The sludge heat pump low-temperature drying machine adopts the strip-forming technology and the closed low-temperature convection drying process, which can effectively prevent the problems of dust, high-temperature decomposition gas, odor volatilization, and gas dust explosion, and is suitable for various sludge drying reductions. Retain and stabilize the components of sludge, and create favorable preconditions for the disposal and utilization of various sludges.