Here is a small plan I quickly put together with a more efficient use of funds than I outlined before which more than doubles MKRs current throughput whilst actually decreasing monthly operating costs. It would cost around $25M AUD, if they sourced 4 second hand ball mills for a bargain it could be a bit cheaper. It also doesn't take into account any costs associated with increasing the non grinding aspect, if needed, to increase the throughput.
By using excess solar energy to build a much finer pre processed stockpile you remove most of the diesel cost involved in grinding. We have gone from one 1800KW ball mill to 3 to cover for the fact solar won't be 24 hours per day, we have 20MW of solar to give us at least 10MW of power into the inverter for more of the day (ie cloudy days, longer into dusk and earlier into dawn). And we have 2 hours of battery storage for the solar grinding so that any bumps in the day are taken care of and to reduce the number of shutdowns/startups due to low solar energy.
That is then run through one of 2 circuits for final grinding and processing. This gives the option of processing 2 different ores at once which is the type of versatility required going forward with MKRs many different ores available to them. The main mill still requires 3MW of power so nothing changes on that front and the current diesel generators can power that by themselves (if needed during the day and overnight) so no need to purchase more diesel generators. The main mill can operate 24 hours a day powered by a combination of sunlight during the day and diesel overnight.
You obviously also don't necessarily have to use ball mills , or even single large ones, for the solar powered grinding, it could be any setup tweaked for the ore you are handling and even different grinding circuits for more than one ore type. This gives them the luxury of being able to purchase a variety of second hand equipment at bargain prices to do the job. It is just about getting the ore into a much finer form, for free as it is powered by the sun, before it then goes through their mill.
As to increasing recovery rates when you have your pre-grinding done essentially for free you can get it into a form that will allow higher recovery rates. Most people here are probably aware the reason recovery rates are only 75-80% is because that it is just what is cost effective when every minute you are running you are burning diesel and money.
