This invention is related to a novel chemical process for extracting and recycling lead from lead acid battery paste and lead ores using a batch of non-acidic and non-hazardous solvents. This method is based on the complete dissolution of all lead compounds except metallic lead at ambient conditions and without using furnace or strong acids to extract lead. The solution is then reduced to metal lead by multivalent metal nano powder (lead reduction promoter catalysts) without employing an electric current.
This solution can be dissolved using a high-speed stirrer without emitting any kind of toxic gas at a pH ranging from 6 to 8. The sponge lead was then converted to cold press ingot after filtration. The extracted lead has a purity above 95% and no further purification is required. This method can also be used to extract lead from ore such as PbS by one step converting process.
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The novel process is able to:
Lead is a versatile and strategically important metal resource for the industrial development and global economy as it is intrinsically associated with automotive, back-up power and energy storage for renewables. Due to its toxicity, industry related with lead production, recycling, application and consumption must deal with public health and environmental concerns from lead emissions, especially in lead smelting, lead-acid battery production and recycling.
The secondary lead produced by recycling process has gradually become the major source of lead in many areas of the world, which will continue to dominate the global lead market. The secondary lead output in developed countries vastly exceed that of primary lead and globally recycled lead accounts for just over two-third of the world output of refined lead. Generally, discarded lead acid batteries (LABs) are the main resource of secondary lead, more than 85% in the total amount of secondary lead.
As disposing spent lead is not an option, recycling of spent lead-acid batteries has already proved its value. Nowadays, most of the secondary lead recovery plants are based on pyrometallurgical methods. The emission of sulfur oxides, nitrogen oxides and lead-containing particulate matters from the pyrometallurgical route constitute a serious consequence for the local environment and human lives. Furthermore, major lead poisoning incidents and high lead contamination near the lead factory have already been of great concern to the public. Therefore, a new environmentally friendly method for recycling lead is a necessity for this industry.