LEAD
The United States produces about one-third of the lead in the world. The remainder comes from Spain, where the production remains about the same from year to year; from Germany, where in spite of higher prices production is growing less; and from Australia and Mexico, in both of which the supply is rapidly decreasing.
These facts show that the lead resources of the United States will be drawn on heavily in the future. The production of the United States increased from about 70,000 tons in 1880 to 365,000 tons seventeen years later, and if continued the yearly production by 1920 will amount to 580,000 tons, or more than a billion pounds.
The principal lead-producing states are Missouri, Idaho, Utah, and Colorado. In Missouri it is probable that the present rate of increase could be kept up for at least fifty years. The other states could keep up the present production for many years but could not greatly increase it without exhausting the supply.
As with most mineral resources in the United States, it is only the richest ores that are now drawn upon (except where lead is a by-product extracted with some other ore). If prices would advance, so as to make the low-grade ores profitable, the amount of our resources would be greatly increased.
There is little waste in the mining or smelting of lead ores, and the slag, the waste, is always ready to be used again. In the refining and concentrating of lead the loss often amounts to as much as fifteen per cent. or twenty per cent. The best way to prevent final loss is to store all refuse until such time as the reworking becomes profitable. Improvement in methods has been great in the last fifteen years but more economical methods everywhere will be one of the necessities of the future. We can see that the lead resources of the United States are not large and that when our own supply is exhausted we can not turn to the rest of the world.
The waste in mining is not large, and most of it can not be avoided at present prices; so that for the conservation, which we see is so important, we must turn to the uses of lead. The most necessary of these is for lead pipes in plumbing. Another use is for war supplies, which not only makes heavy drains on our stores of coal and iron, but also on lead, which is much less plentiful.
One ton out of every three produced in the United States is used in the manufacture of white lead and consumed as paint. This, of course, is entirely lost, and it seems that some other material might be used, instead of so valuable a mineral, especially when the resource is not abundant. White lead is used more than any other substance for paint, although zinc white has come into considerable use in the last few years. No other nation uses lead paint to such an extent as does the United States, partly because no other nation could afford so general a use of such an expensive material, and partly because so many wooden buildings are erected. By using brick, stone, or cement, of which we have practically an unending supply, to take the place of wood, our store of which is rapidly disappearing, we could avoid much of the drain on our mineral resources which are used for paint.
As production and price advance a greater quantity of lead is remelted. About 25,000 tons are returned to use each year.