RE: Research9 Mar 2022 18:35
"... Instead of smelting, laterite nickel can also be handled by a lovely-sounding process called high-pressure acid leaching (HPAL). The CO2 produced by HPAL is about one third that of laterite smelting, but still several times as much as even the more carbon-intensive variants of sulphide processing. Not only that, but HPAL produces large amounts of waste — unstable and hazardous tailings, acid slurry, and magnesium sulphate effluent. The difficulty in storing these products in areas of high rainfall (as laterite nickel producing regions are) and earthquake-prone locations has led to the proposal that they should be discharged into the deep sea. This is not an environmentally friendly option. For all these reasons, HPAL is the second way laterite nickel is dirty.
The third way laterite nickel is dirty is through the destruction of tropical rainforest — and not just any rainforest. Because of accidents of climate and geology, laterite nickel deposits are most extensive in Indonesia and the Philippines. These two countries account for 75% of laterite-nickel production. They are also considered biodiversity hotspots in that they are exceptional in the number and uniqueness of species that occur there. Therefore, effective conservation of their biological resources is a high priority.
Because laterite nickel deposits are widespread, low grade, and shallow, strip mining is the only realistic method of obtaining this ore. The first step in strip mining is, naturally, to remove everything growing on the surface. I estimated that over 40% of the nickel mines on the island of Sulawesi in Indonesia stripped intact rainforest to get to the nickel ore. Recent assessments by the United Nations and others have highlighted the accelerating rate of species loss on our planet. Strip-mining for laterite nickel is a threat to efforts to arrest and reverse these trends.
Importantly, due to the geochemistry involved, laterite nickel deposits often form along ridges and hilltops. A moment’s thought is all it takes to predict what will happen when heavy tropical rain falls on ridges and hilltops from which all vegetation has been removed. The rains will wash away any loose dirt, sand, or grit that has been exposed. Indonesia and the Philippines are island nations, and none of the islands with laterite nickel are very large. As a result, sediment washed off of nickel mines is, in short order, carried out to sea. In the tropics, “out to sea” means onto coral reefs. This is the fourth way laterite nickel is dirty nickel. Coral reefs around the world are already in crisis due to rising temperatures, pollution, and exploitation. Sediment settling out of discharge from streams and rivers severely exacerbates these issues. Coral reefs are the rainforests of the sea, and are also important in supporting local livelihoods through fishing and tourism. ..."
https://www.batterymaterialsreview.com/ourblogs/is-it-time-for-lower-grade-nickel-sulphide-projects-to-shine/