From approximately the mid 1980’s until the present time we have relied on converting a smelter byproduct to metal and antimony oxide. USAC also supplemented the feed with material from smelters, mines and catalytic plants in Europe, Bolivia, Peru, Australia, Honduras, Guatemala, Idaho, Alaska and other U.S. States.
KEY TO FLOW DIAGRAM
- All tons are metric (mt).
- C & M care and maintenance.
- Ag is silver in ounces per metric ton. Au is gold ounces per metric ton.
- Sb is antimony.
- tpm is metric tons per month; tpy is metric tons per year.
- tpd is metric tons per day.
- DSO is direct shipping ore.
- PM is precious metal.
- n/a not available.
- Cons are concentrates.
- SA is sodium antimonite.
- SRF furnaces are used to fume low grade ores due to slag removal, but are also used for high grade ores. Their feed capacity will vary from 1,000-1,800 ppd, and the production is dependent on the feed grade. Four SRFs are being installed, and 5 more are being permitted.
- Calculations at Madero, Mexico are based on oxide DSO and cons at a grade of 30%.
- An LRF is designed for feed >50% Sb. They will handle up to 10 tpd for roasting. We are now permitting one LRF.
- Calculations at the Montana smelter are based on the reduction of SA at a grade of 48%.
- All PM is removed in Montana and the capacity of the PM plant is large.
- Calculations for tri-sulfide are based on the tri-sulfide containing 70% Sb.
- For quick calculations that are not necessarily real accurate we use $10,000/mt Sb.
- Mines have been put on C & M until the smelter capacity is brought up.
- Guadalupe concentrates are excellent feed and are necessary for tri-sulfide production which is worth much more than the other oxide and metal production.
- Los Juarez production will be restarted after the completion of the mercury recovery unit (MRU) and leach circuit.