o xygen from the metal o xides to form CO 2 while the ores are reduced to molten base metals which then combine in the solution In silicon production one of the important byproducts of this process is silica fume which can be used in the construction industry Figure 30 Submerged electric arc furnace source Elk em Product quality requirements impose major constraints in the choice of raw materials such as coal and cok es Natural gas cannot be used as a reducing agent as smelting needs elementary carbon The energy consumption per ton of metal difers greatly from one ferroalloy to another The production of ferroalloys is a highly energyconsuming process because high temperatures are needed for the reduction of metal o xides and smelting related to the fashfurnace can consume high levels of electricity up to 2628 MWht nick el 75 of which is related to slag treatment 148 On average the energy use for nick el producers in Europe is 7080 electricity and 2030 natural gas 149 Between 2011 and 2016 the emissions from Nick el production remained stable from 346 kt CO 2 eq in 2011 to 349 kt CO 2 eq in 2016 in the EU28 and Norway The CO 2 intensity was reduced by 5 over the same period from 191 to 184 Given the electrointensity of nick el refning the indirect emissions represent at around 85 by far the highest share of overall CO 2 emissions 150 Figure 29 C O 2 eq emissions in Nick el production EU28 Norway Source Nick el Institute 56 Silicon FerroSilicon and FerroManganese F erroalloys and silicon are principally produced in submerged EAF electric arc furnaces The process is the carbothermic reduction of o xidic ores or concentrates in which carbon in the form of cok e metallurgical cok e coal or charcoal is normally used as a reducing agent 151 In the EAF passing current through graphite electrodes suspended in a cupshaped refracto rylined steel shell accomplishes heating Carbon reduction of the metallic o xides occurs as both cok e and graphite electrodes are consumed The carbon in the electrodes reacts with the 148 Data from Harvjavalta refnery and Harvjavalta Flash furnace USGS 2011 149 Nick el Institute 150 Ibidem 151 R aw material inputs also include raw materials ores reductants cok e siliconbases ferroalloys aluminium iron additions iron ore or steel scrap and fux es lime magnesia dolomite limestone fuorspar etc Direct emissions kt CO Indirect emissions kt CO 34604 34846 20 1 2016 2011 2011 2016 290 11 289 26 5593 59 60 MET ALS IN A CLIMA TE NEUTRAL EUROPE A 2050 BL UEPRINT 48