Page 58 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

GENERAL FEATURES 57 Mexico ores and concentrates. In cases where the smelter requires silica, lime, or iron for fluxing purposes, low-grade ores may be accepted by it without penalties or smelting charges being levied, and the usual rates paid for all recoverable metals. Several old dumps have been treated on this basis. Normally, however, a base smelting charge of $2.50 to $5.00 per ton is imposed, payment is made for recoverable metals based on the current market price with certain reductions, and charges are made for undesirable constituents or other objectionable fea- tures of the ore. Metals are not paid for in full amount, deduc- tions being made to take care of metallurgical losses in smelting and refining and for metal handling costs such as refining, mar- keting, shipping of bullion, interest on capital, and the profit to the smelter. Although the amounts paid vary within wide limits, the following may be considered as typical for Sierra County
ores :
Gold—.0l to .05 oz. minimum, pay for 95-100% at $19.00-20.00 per25
Silver—.5 to 1.0 oz. minimum, pay for 95% at market price less 3 1/3c. Lead-3.5 to 5.0% minimum, pay for 90% at market price less 1.5c
per lb. Lead not paid for in copper ore smelted in a copper furnace. Copper-8 lbs. deducted per ton, pay for 95% of remainder at market
price less 21/2c. (Market price less 334c in a lead ore.)
Zinc—In a high-grade zinc ore or concentrate usually 75-85% is paid
for and smelting charges are high. Zinc in a. copper or lead ore is lost in smelting, adds to smelting difficulties, and as a rule is penalized at the rate of 30c per unit in excess of 5%.
Penalities are charged for the undesirable constituents in an ore and premiums generally allowed for the desirable fluxing constituents. Some typical premiums and penalties are as
follows:
Silica-10e to 12c penalty per unit for total silica or insoluble. Iron—Paid for at 5c to 6c per unit when silica is penalized. Manganese—Paid for at 5c to 6c per unit when silica is penalized. Lime—Paid for at 8c per unit in amounts exceeding 2%.
Sulfur—Copper smelters usually ignore the sulfur content, but lead
smelters penalize, and in one case sulfur in excess of 1% was penalized 20c per unit.
Arsenic, Antimony, Bismuth—Allow 1% free of these elements com- bined and charge for excess at $1.00 per unit, but the penalty varies widely.
Moisture—Allow 12% free and charge 20c per unit in excess. This will affect only flotation concentrates.
Miscellaneous—A charge of 50c per ton may be levied for ore received in sacks. Special sampling charges may be imposed for shipments below a certain minimum number of tons.
Railroad freight charges from the nearest shipping point to the smelter are paid by the smelter and deducted from the amount due the shipper on his ore. Freight rates are determined by the railroads and increase for the same haul with the value of the ore.
An excellent rule to follow and one that is given careful consideration by many experienced mine operators and mining companies when considering new properties, is that after liberal
25ee footnote. nave 59.