3.3. Functional unit and goal of LCA study<br>The functional unit in consideration for LCA in mining could be<br>of 1 kg of selected mineral, or 1 tonne of selected mineral, or a mega<br>tonne of that selected mineral. The goal of the LCA works is to<br>analyse the effects of a product or process based on their system<br>boundary and categorise their emissions (Teh et al., 2017): the<br>materials, energy (in the form of renewables and non-renewables,<br>resources, organic and inorganic chemicals are identified as the<br>material inputs in an LCA study (Mahmud et al., 2018b, 2018c,<br>2018d). The output product, waste emissions, by-products, and<br>emissions to soil, water, and environment are considered as material<br>or process outputs (Althaus and Classen, 2005).<br>3.4. Life cycle inventory datasets<br>The life-cycle inventory datasets were collected from several<br>sources like company reports, published literature, renowned databases<br>like EcoInvent, USGS, AusLCI. However, very few datasets<br>are focused on global context. Datasets can be presented as global<br>datasets, regional datasets, or country-specific datasets. For<br>standardising the datasets, the collected sets of data are quantified<br>and aggregated, validated, averaged, and finally represented in the<br>form of mine irrespective datasets. The source of these datasets<br>could be originated from mining company reports, published<br>research works, books, media, and so on (DEE, 2017; EPA, 2018). A<br>global dataset could be generated after data collection from several<br>mining companies of different geographic regions, aggregating,<br>averaging, checking, and data validation. Most of the metal life<br>cycle inventory datasets are regional, which is confusing because<br>technology mix, heat mix, and grid mix vary from one company to<br>another, one country to another, and from one region to another.<br>Another major difference is most of the metals could be mined in<br>alternative routes and alternative techniques. It is hard and not<br>available to get the inventory datasets for each of those mining<br>processes.
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