I found this aricle that explain how the furture amd metal markets work, It refers to the London Metal Exchange but I think you'll fing it interesting.

Cashing In
As in whatever other industry, producers of minerals have to find a market for their products. Only through this can they profit from their efforts.

Some metals have a terminal market which is established – this is an institution where metal dealers bid for quantities of metal, and establish a daily price for it. Other metals are given their price by individual producers, who respond to the market for the metal by raising the price in times of strong demand, and lowering it when demand falls off.

The most important international terminal market is the London Metal Exchange (LME) in London, England for base metals. The London Metal Exchange’s member firms specialize in the services of metal brokering, facilitating the purchase and sale of metals to London Metal Exchange specifications by clients. Metals which are bought and sold at the exchange include lead, copper, aluminum, zinc and nickel by way of bidding rings two times a day. The London Metal Exchange functions as a clearing market for metals, offering contracts, both spot and futures. Its principal role is to give a service to clients who are in search of fixing prices, hedge inventories and most of the time manages risk from volatile commodity prices.

A buyer of futures purchases a contract for a certain amount of tonnes of metal, even though that metal has not been processed or mined yet. The contract specifies the metal which will be delivered at any time in the future, almost always in three months’ time. The price which is offered will be different, and generally higher, than the spot price. Such futures and the warrants which represent them are negotiable very much the same way as spot metals.

The same reasoning underlies the exchanging of futures. That is, buyers look for protection against prices that go up by hedging against current sales. Sellers of futures contracts, almost always metal producers, make sure that their metal can be sold at the contract price, thus "locking in" their profits.

Quotations from the London Metal Exchange are the basis for the prices of transaction in the most part of the world. The quotations represent actual day-to-day purchases between sellers and buyers, and they are published in the daily press and released to news services.

In North America, the Commodity Exchange (COMEX) in New York is a principal terminal market in gold, silver and copper. It tends to be a speculative market, attracting a much stronger proportion of individual investors than does the London Metal Exchange (LME). In London, the main business is with trade accounts using terminal markets for business purposes.

Futures exchanges are generally markets of hedge. A very small tonnage of the total sales on the hedge markets ever actually changes hands, physically. Most of the sales for physical supplies (metal producers selling to manufacturers of metal-based products) are handled by producers and/or metal traders. The merchant price of metal most of the time fluctuates on a daily basis in line with movements on the London Metal Exchange and United States exchanges of commodity.

Producers have a set price that is fixed periodically in answer to prices on the terminal markets. These are called producer prices. It is also common for producers to sell their metal at a fixed premium to the daily settlement prices on the London Metal Exchange (LME) or Comex.

LS