Security Destruction And Resources Recycling For Computer Hard Disk Drive And Random Access Memory Storage Medium

Computer brings us a lot of convenience, speediness and comfortwhile its abandonment brings us a lot of waste electrical and electronicequipment (WEEE). Hrad disk drive (HDD) and Random AccessMemory (RAM) have the characters of data security and resourcebility,which raised new challenge of security destruction and resourcesrecycling of waste electronical storage medium (WESM). Therefore, thispaper studied the security destruction and resources recycling of WESMand put forward relevant methods, taking HDD and RAM as researchobjects.For magnetic WESM represented by HDD, static magnetic fieldwas employed to degauss HDD disk, whose magnetic domain structurewas then observed by magnetic force microscopy. It can be discoveredthat the residual information was completely cleared. During degaussingprocess, the disk should keeping parallel to the direction of magneticfield. A satisfying degaussing effect can be achieved when HDD wastreated by3500Gs magnetic field for6-10s. The mass fraction ofaluminum alloy in the entire HDD is up to more than70%, makingaluminum alloy a very valuable recycling resource in HDD. The coatingof aluminum alloy in HDD can be removed by heating for24min in400℃in order to transform this waste material into secondary aluminumalloy. A comprehensive treatment technology was developed, whichprovided a research path for waste HDD integral resourcebility.For semiconductor WESM represented by RAM, This paperadopted crushing method to destruct RAM in security. Thefragmentation size distribution of crushed RAM can be simulated byR-R distribution model. The fitting correlation coefficients by linear equation and quadratic equation are0.9624and0.9986. The dynamicsrules of RAM crushing can be simulated by first-order kinetics model,R2=0.94377. It is claimed by this study that when RAM is being crushedfor4min by two-step crushing, more than19%fragmentation will becrushed whose grain diameter is smaller than0.1mm. And the contentof Si at this fragmentation size is50%higher than other’s, reaching thenational destruction requirement. R-R distribution model, first-orderkinetics model and area theory can be used to analyze the process ofRAM crushing with certain guiding significance.The key point of semiconductor SM resourcebility focused on theseparation of conductors, semiconductors and nonconductors in crushedmaterial. In this paper, each two-component material system formed byevery two of above three materials was selected as feed to research highvoltage electrostatic separation (HVES). Then two-stage and three-stageHVES for three-component material system were designed. In two-stageHVES, the nonconductors can be separated well, while the conductors orsemiconductors cannot. Three-stage HVES solved above problems,making the separation rate of conductors, semiconductors andnonconductors reached82.5%,88.0%and98.1%. In three-stage HVES,the voltage of stage1,2and3was30kV,5kV and5kV; the rotation ofstage1,2and3was50rpm,80rpm and80rpm.This paper adopted static magnetic degaussing method to destructHDD (magnetic WESM) and realize its entirety reclamation accordingto its components form. Crushing method was adopted to destruct RAM(semiconductor WESM) and multi-step HVES was adopted to separatecrushed RAM material in order to realize its reclamation.