2648 Table 2 – Details on copper concentrator flow sheet Elementary stream Associated emission Plant units applicable Additional information Inputs Electricity Scope 2 Crushing, grinding, beneficiation, dewatering Location must be known (more specific EF) Grinding media Scope 3 Grinding Material must be known (more specific EF) Mill liner Scope 3 Grinding Material must be known (more specific EF) Reagents Scope 3 Beneficiation, dewatering Collector: AERO MX-5141 (Xanthate) Frother: MIBC (foaming agent) Activator: Butyl potassium xanthate pH Regulator: Lime (CaO) Flocculant: Magnafloc (polyacrylamide) Outputs Copper concentrate - Dewatering Reference flow 4.2.1 Scope 1 emissions Scope 1 emissions are direct emissions from sources within the system boundary [5]. In this scenario, these could potentially emerge from reagents reacting with the ore; however, it was assumed that no such GHG emissions are produced. This has been confirmed (partially) by examining the MSDS59 of xanthate. Xanthate may decompose to products like CS2 and H2S; however, these are not officially GHG emissions and are unlikely to convert into CO2 or other GHG. Other potential scope 1 emissions could be from fossil fuel combustion (e.g., backup generators, or mobile equipment). However, no significant fuel consumers exist within the system boundary; accordingly, Scope 1 emissions are assumed to be zero. 4.2.2 Scope 2 emissions Scope 2 emissions refer to indirect emissions from the generation of purchased electricity, steam, heating, and cooling consumed within the system boundary [5]. Electricity is used throughout the plant, across all units. To estimate GHG emissions from electricity use, power usage data for each plant unit are collected, along with the appropriate EF. According to the IPCC Guidelines [12], the EF must be locationspecific, hence the Chilean grid EF from Ecoinvent of 0.5628 kg CO2e/kWh is selected (see Table 1 for comparison across all three case studies). 4.2.3 Scope 3 emissions Scope 3 emissions refer to all other indirect emissions, such as those from the production of purchased goods [4]. In this study, these include the production of materials that wear in the grinding plant units (mill liners and grinding media) and the reagents consumed in the flotation and dewatering units. Wear materials: 59https://reviewboard.ca/upload/project_document/EA0809004_MSDS_for_Potassium_Amyl_Xanthate.PDF
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