Method for extracting lithium from lepidolite through PVC pyrolysis

Abstract

The invention provides a method for extracting lithium from lepidolite through PVC pyrolysis. The method comprises the following steps of: (1) performing low-temperature pyrolysis on cleaned and driedPVC plastic under inert atmosphere to obtain HCl gas and tar; (2) mixing lepidolite ores with calcium oxide, and performing defluorination roasting after uniformly grinding to obtain defluorinated lepidolite ores; (3) leading HCl gas obtained in the step (1) into the defluorinated lepidolite ores obtained in step (2), and performing chlorination roasting to obtain clinker; (4) leaching the clinker obtained in step (3) with water, and performing solid-liquid separation to obtain leach liquor; and (5) adding an alkali precipitator into the leach liquor obtained in step (4), and filtering afterreacting to obtain lithium carbonate solid and filtrate. The method provides a novel idea for comprehensive utilization of PVC waste, reduces pollution, on environment, of PVC waste, reduces production cost of lithium carbonate, realizes comprehensive utilization of PVC, and generates great economic benefits.

Description

technical field [0001] The invention belongs to the field of metallurgy, in particular to a method for extracting lithium from lepidolite by utilizing PVC pyrolysis. Background technique [0002] Lithium is known as "the energy metal that promotes the progress of the world". As a new energy and strategic resource, lithium is widely used in various fields of the national economy. Not only plays an important role in traditional consumer fields such as glass, ceramics, lubricants, etc., but also promotes the development of high-tech fields such as lithium batteries, nuclear energy, aerospace and other fields, especially in recent years with the new energy automobile industry With the rapid development of electronics industry and the global market demand for lithium is increasing year by year. [0003] my country has abundant lepidolite resources, among which Li 2 O content is generally 3% to 5%. At present, the methods for extracting lithium from lepidolite mainly include li...

AI Technical Summary

Problems solved by technology

Among them, gaseous chlorinating agents, especially HCl, as chlorinating agents can greatly shorten the chlorination roasting cycle and roasting temperature, and have attracted the attention of many scholars. High pollution and other reasons have greatly limited the application of HCl in chlorination metallurgy, and there are few reports on the use of HCl in lepidolite chlorination to extract lithium. The application in the field of chemical metallurgy is of great significance

[0004] PVC is a high-molecular organic polymer material. Due to its characteristics of flame retardancy, chemical resistance, high mechanical strength and good electrical insulation, its production cost is low, and it is widely used in the production of hard products and films such as pipes, plates, profiles, etc. , wire skin, artificial leather, shoe soles and other soft products, my country’s PVC production capacity has grown rapidly since 2002, and its output has increased significantly. By 2016, PVC output will be close to 16 million tons, and my country’s annual PVC waste that can be effectively recycled accounts for 10% of the output. About 20%, waste PVC that is not recycled will bring huge pollution to the environment, and at the same time bring huge economic pressure to environmental protection

Since PVC molecules contain nearly 60% chlorine, a large amount of HCl gas will be produced during the pyrolysis process, which can be considered as a solid release source of gas chlorinating agent, but direct combustion of PVC in the air is likely to produce carcinogens such as dioxin , limiting the comprehensive utilization of PVC

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