IPO - Jupiter Mines Limited, page-145

CabinetMember to answer your question.
Much of OMH manganese ore is sold to the Chinese smelters.
"OMM’s Bootu Creek ore stepped in to fill the supply gap, generating additional value by leveraging its unique chemical composition widely favored by Chinese silicomanganese smelters."
OMH can also use Tshipi Mn ore for its Sarawak smelter. OMH does point out that it does sell to the Chinese when its making a good profit on Bootu Ck ore.

OMH is also developing its own smelter feed from the stockpile of otherwise waste material.
"1. Complete a turnkey retreatment plant project at Bootu Creek by middle of 2019, with a capacity of 200,000 to 300,000 tonnes per annum. We estimate that this will be able to generate at least 10 years of cost-effective sinter feed for our Sarawak smelter. "

The OM Sawarak smelter does work on a smaller margin than the Tshipi mine, OMH overall had a profit margin is 21% as per the latest financials. ( But this is overall and I suspect that the alloy profit is far higher but will use this figure).
However the smelters are still ramping up and the next financial report will give a proper indication of the operation. On current ferro and manganese production you are looking at
FeSi 9 furnaces at 62 tonnes/day =203,670 tonnes pa ( say 200,000) manganese furnaces 3 x SiMn at 105 tonnes/day = 38,325 tonnes pa plus 3 x FeMn at 155tonnes/day = 169,725 tonnes pa.
So lets say 400,000 tonnes pa for 15 furnaces, still one to fire up with silicon metal (US$2,500/tonne)
Current price of FeSi is US$1450/tonne and SiMn US$1300/tonne FeMn slightly more .
Total earnings more than AUD$700 million, omh share is 75% = $525 million profit 21% = $110 million.

Not only is OMH the only FeSi producer on the ASX, its also becoming one of the worlds largest suppliers.
In 2017 OMH exported 182,316 tonnes of Ferro Silicon. Compare this to ALL "China exported 373,318 tonnes of ferro-silicon in 2017"

Alloy sales last year (OMH share )was AUD$380million, so we have an increase of $120 million due to increase furnaces from end of last year.
Alloy sales are only a part of OMH as you can see from the Financials. total sales in the second half were $728 million, so annually will be $1.5 billion+