A method of resource utilization of waste plastics in urban solid waste to promote iron ore reduction

Abstract

A method for recycling plastic wastes in urban solid wastes to promote iron ore reduction comprises the following steps: drying film waste plastics separated from the urban solid wastes, shearing andcrushing the dried film plastic wastes, fully mixing the crushed film plastic wastes with a carbon reducing agent powder, performing low-temperature carbonization treatment at 400-550 DEG C to obtaina carbonization product, crushing the carbonization product to form a reducing agent containing carbon pellets, uniformly mixing and compacting the reducing agent containing carbon pellets with an iron-containing material to prepare carbon-containing pellets, conveying the carbon-containing pellets to a rotary hearth furnace, and performing rapid reduction. The initial reduction temperature of thepellets is significantly reduced and the reduction rate is accelerated to obtain high-quality metalized pellets, and the waste plastics are decomposed and consumed in the reduction process, and provide energy for the furnace heating of the rotary hearth furnace. The method solves a problem that existing direct reduction methods for processing the waste plastics cannot realize the preprocessing offilm thermoplastic plastic wastes in the urban solid waste in the manner of low cost, high efficiency and large scale, promotes the reduction of iron ores, and has the advantages of simple process, short flow, high efficiency, low cost, and good social and economic benefits.

Description

technical field [0001] The invention mainly belongs to the fields of ecological environmental protection and resource comprehensive utilization, and specifically relates to a method for pretreatment of film waste plastic in urban domestic garbage and using it as an iron ore reducing agent, which is used for resource utilization of film waste plastic in urban domestic waste. Background technique [0002] The garbage problem can be said to be a "world problem" accompanying the history of human civilization. With the continuous deepening of my country's new urbanization process, the scale and number of cities are growing explosively. According to the household registration population statistics of municipal districts at the end of 2015, there are 134 large cities with a population of more than 1 million. According to the annual discharge of about 300 kilograms of domestic waste per person, the annual urban domestic waste production is nearly 200 million tons, and it is still g...

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Problems solved by technology

[0007] In the prior art, the Chinese patent (Application No.: 201410348368.7) titled "An iron-based carbon-containing pellet with waste plastic as a carbon source and its preparation method" discloses an iron pellet with waste plastic as a carbon source. Based carbon-containing pellets and their preparation methods, but the patent only uses a mixture of several waste plastics as the reducing agent, and requires the particle size of the waste plastics to be less than 80 meshes. It is difficult to crush plastic waste plastics. The patent does not consider how to economically Efficiently realize the shredding of waste plastics, especially for the film waste plastics produced in large quantities in daily life, this method is more difficult to apply

In addition, a large number of experiments have proved that it is difficult to obtain a high degree of reduction when using waste plastic alone as a carbon-containing pellet reducing agent because the decomposition temperature of the plastic is much lower than the reduction temperature of iron oxides.

[0008] The Chinese patent with the application number 201310578312.6 discloses a method of using waste plastics to directly reduce limonite or hematite to produce iron. This method uses the method of directly mixing and adding waste plastics and coal powder to make pellets Yes, due to the low density of the mixed material and the crushed particle size of waste plastics is 1-3mm, it will inevitably lead to relatively low strength of green pellets, and it is also difficult to deal with the large-scale production of film plastic waste plastics in daily life. In addition, The purpose of this patent is to use waste plastics instead of pulverized coal as a reducing agent to produce pig iron. The reaction temperature of the rotary hearth furnace in this process is high (up to 1370 ° C), which is difficult to realize and the production cost is also high. Moreover, the patent is not based on waste plastics. Low-temperature decomposition cannot provide the characteristics of an effective reducing agent for batching. Equaling the organic volatile carbon in waste plastics to the fixed carbon in coal powder will inevitably lead to a low metallization rate of the pellets and poor melting effect of slag and iron. The final metal iron particles are small, and high-quality pig iron needs to be further crushed, magnetically separated, and briquetted.

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