Silicon:

Silicon is one of the most prevalent substances on earth, only second after oxygen. It can be found in a variety of places (China, Brazil, Canada and Russia are the biggest producers) and is used in almost all contemporary electronics. It became a massive influence in the 1970s and 1980s with transistor and chip technology. This is important in the context of scanners as the transistors and chips create the CCD, which is one of the main costs of the scanner. Furthermore it reflects some of the larger issues apparent in developing scanners. Silicon is usually found in sand which contains high purity quartz rock ("Refining Silicon"). After gathering this material in large quantities, it is treated in a furnance with temperatures between 1500-2000 C ("Refining Silicon"). This produces metallurgical grade silicon through the following reaction: SiO2 + C → Si + CO2 ("Refining Silicon"). Therefore a byproduct of this reaction is carbon dioxide, which is one of the most harmful gases and has contributed heavily to global warming. Furthermore carbon dioxide is toxic to humans and as such presents safety concerns for works.

After this initial process, silicone is then subjected to another treatment: reacted with hydrocholoric acid ("Refining Silicon"). This is to reduce impurties and produces a silicon-hydrate and di-hydrogen (Si + 3HCl → SiHCl3 + H2) ("Refining Silicon"). It is boiled at a variety of temperatures which allows the impure elements to be filtered ("Refining Silicon"). The silicon-hydrate is then reacted with hydrogen at 1100C in order to produce the following reaction: SiHCl3 + H2 →Si + 3 HCl ("Refining Silicon"). The final product includes a <99% silicon as well as hydrogen chloride gas ("Refining Silicon"). This again is a dangerous process for workers as it exposes them to hydrogen chloride gas, which can be toxic when it comes into contact with skin. If exposed to water, which constitutes the majority of a human's body, it immediately becomes hydrochloric acid thus corrosively burning skin and resulting in permanent damage and death ("Refining Silicon"). Therefore international sanctions have been created in order to protect workers. However, many companies do not follow these sanctions strictly and workers often become sick and scarred. This is particularly prevalent in countries like China that continue to ignore UN laws governing harmful chemical production.