Proof of concept to investigate a cost effective, environmentally safe closed loop system, to recover metals from spent pot liners / crucibles used in the melting of all types of metals, either during the initial smelting stage or metal purification stage

废锅衬里(SPL‘s)是在铝(和其他金属)冶炼电解过程中，在坩埚/锅的脱衬过程中产生的废料。SPL由碳和各种惰性元素组成，也包括氟化物和氰化物，因此是危险废物。它被认为是一种难以处理且成本高昂的废物，因为：·它有与水结合并产生爆炸性气体的倾向。·氰化物的存在处于有毒水平，对人类和其他有生命的生物具有潜在的致命性。在世界大多数地区，固体废物作为一种危险废物受到严格监管，并受到以下约束：·《控制危险废物越境转移及其处置巴塞尔公约》。·运输到冶炼厂以外的地方，监管要求日益繁重。·越来越多的国家禁止垃圾填埋有效处置铝电解槽阴极的固体废物是一个重大的环境挑战。这不仅是铝工业的一个商业机会，也是一个商业机会，因为残留金属--有可能再利用惰性残渣材料制造新的罐衬或作为其他制造的投入品，例如骨料。由于材料的毒性，这种重复使用以前并不吸引人。我们的想法是用我们正在开发的一些新的材料分离方法进行进一步的研究，并将这些方法应用到SPL的材料分离中。我们进行了简单的测试，表明金属有一定程度的优先还原和分离。进一步的研究和实验将使我们能够更充分地探索SPL的这些新工艺。我们建议将残留的金属材料放在Wilfley工作台(或类似设备)上处理，并添加次氯酸钙，使微量的氰化物转化为惰性氰化物，同时将氟化物转化为惰性氟化钙。然后，惰性材料可以安全地重新用于制造。

Spent pot linings (SPL’s) are the waste material generated in the de-lining of crucibles/potsfollowing the aluminium (and other metal) smelting electrolysis process. The SPL iscomposed of carbon & various inert elements but also fluoride and cyanide and is thushazardous waste. It is regarded as a difficult and expensive waste stream to deal with because:• It has a propensity to combine with water and generate explosive gases.• The presence of cyanide at toxic levels potentially lethal for humans and other livingorganisms.SPL's are highly regulated as a hazardous waste in most parts of the world & are subject to:• The Basel Convention on the Control of Trans-boundary Movements of HazardousWastes and their Disposal.• Increasingly onerous regulatory requirements when shipped beyond the smelter.• Bans on landfill in an increasing number of countriesEffective disposal of SPL’s from aluminium reduction cell cathodes is a significantenvironmental challenge for the aluminium industry but is also a commercial opportunitybecause of the residual metal & the potential to reuse the inert residual material for makingnew pot liners or as input for other manufacturing e.g. aggregates. Such reuse has beenunattractive previously due to the toxicity of the material.Our idea is to conduct further research with some of the novel methods we are developing formaterials separation and applying these to SPL’s. We have carried out simple tests whichshowed a degree of preferential reduction & separation of the metals. Further research &experimentation will enable us to explore these novel processes more fully for SPL’s. Wepropose that the residual, de metalled material can be treated on a Wilfley table (or similar)and with the addition of calcium hypochlorite to render the trace amount of cyanides into inertcyanites at the same time converting the fluoride to inert calcium fluoride.The inert material can then be safely re used in manufacturing.