RE:RE:RE:RE:RE:RE:RE:Reality CheckThe details of every process is unique to that particular plant, and is usually proprietary info, so I don’t know exactly but typically sulphuric acid is used to “leach”/extract minerals out of the ore. This can be done by pouring acid on a pile of low grade ore (heap leach). In the case of higher grade ore, like Boleo, they will mill the raw ore, to get a slurry with relatively high concentration, put it in a leach tank, and add the acid in there. The sulphuric acid exiting the tank contains dissolved copper, and other metals (Boleo’s will probably have cobalt, zinc, and manganese in it too). This is reffered to as a “pregnant” leach solution (PLS)- it goes into the electrowinning cells. There they add electricity to make the copper in the solution attract to plates in the cells. Your question is about the acid exiting the electrowinning cells- where does it go? Well, at Boleo it will probably have other minerals dissolved in it that they are after, so they may send it to a cobalt extraction circuit (cobalt can be electrowinned also), or a zinc extraction circuit, or whatever they’re trying to get out of it. OR, they may return it to the leaching tanks where it will absorb more copper and go right back to electrowinning. Acid can be recycled several times. Eventually it will lose it’s effectiveness, and they will dispose of it. Again, I don’t know how they will do it at Boleo, but sulphuric acid can be neutralized with lime. Typical acid neutralization is: mix lime with the acid in an agitated tank, the contents of the tank will be pumped to a clarifier, the impurities and solids settle to the bottom and are pumped to a tailings pond, the overflow/effluent is clear and safe for discharge into the environment.