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pressure followed by a stagnation of the consuming markets, both domestic and foreign.

Seven months after the signing of the armistice, there is little relief in the situation. Zinc has been exported in larger quantities than before the war but domestic consumption is at a low ebb. Mines, mills, and reduction works all over the country are idle or being operated at much reduced capacity. Imports from all countries except Mexico and Canada have practically ceased, and the quantity imported is not large as compared to that imported during the war though much greater than that which came in before the

war.

SUPPLIES.

Zinc is found in nature as a sulphide and in various oxidized ores. Practically, the essential differences between the two occurrences are: (1) The former must be roasted before it can be smelted, but (2) it usually contains a much higher percentage of zinc. Zinc minerals are widely distributed over the world and are frequently associated with ores of other metals, notably lead. Until quite recently zinc was always considered an undesirable constituent of such ores, but now improved methods of ore treatment permit the commercial separation of the zinc, and the zinc contents of complex ores have become an important factor in the zinc resources of this and other countries.

The United States is the largest producer of zinc ore in the world, furnishing, in 1913, some 35 per cent of the world supply. Oneseventh of the total output of the world was derived from one district—the Joplin-Miami or "Komspelter" region-situated in and about the southwestern corner of Missouri. Next to the United States, Germany was the largest producer in 1913; the output amounted to one-fourth of the world's total. Australia furnished 15 per cent, and the remainder came from a score of countries, no one of which furnished any considerable fraction of the total supply.

Since the location of zinc reduction works is determined by availability of fuel and labor supply rather than by proximity to ore deposits, zinc ore and concentrates are important factors in foreign trade and are transported long distances. The ore from North American mines must be largely transported by rail, whereas the ores of other countries are transported to smelting works by water. Australian concentrates are normally transported to European works for treatment. These concentrates, formerly controlled by German metal syndicates, are now under contract to the British Governmemt.

The zinc supplies of the future may be expected to come from the above-named countries in somewhat the same proportions. Burma, however, is becoming of great importance and Siberia is capable of large ore production, although the latter country is handicapped by political disturbances and its distance from large consuming centers. The position of Germany is much altered by the inclusion of the Silesian deposits and reduction works within the borders of the new state of Poland, and this State also includes the mines and smelteries that were formerly in Russian territory. Only about one-third of the prewar output of Germany came from Rheinland and Westphalia, which are the only zinc-producing regions that are left in Germany according to the boundaries defined by the first draft of the peace treaty. Increased supplies of ore are to be expected from Canada, Mexico, Chile, Peru, and Bolivia.

From the American viewpoint, Mexico is the most important of these future producers, as most of the Mexican output in the past has been smelted in the United States, and in case the Mexican mines can again be worked with any degree of safety this country will be the logical market for the product.

TARIFF FEATURES.

Prior to 1905, foreign competition was of no consequence in the zinc ore market. A little ore had been imported at various times, but the quantity was insignificant. But in that year and thereafter until all zinc ores were made dutiable under the act of 1909, considerable quantities were imported from Mexico and Canada, some with, some without, payment of duty. After the duty of 1 cent per pound was placed on the zinc contents of ore containing 25 per cent or more of zinc, the imports fell off to a very small amount. This duty, however, was reduced to 10 per cent ad valorem or an equivalent of from 0.2 to 0.4 cent per pound in the act of 1913.

At the time of the tariff change in 1913, mining was at a low ebb in Mexico and imports of zinc ore actually decreased, due to political conditions. When these are adjusted, active competition may be expected from the large, cheaply mined deposits in that country. Zinc ore may be imported from Canada and South American countries, but the important factor is the Mexican situation, as under normal conditions Mexican mines can furnish large quantities of zinc ore to American smelteries at much lower costs than those at which some American mines can operate.

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1 Zinc contents. 2 Exports consisted wholly of high-grade willemite ore from New Jersey. Assumed content of 50 per cent zinc for calculation of ratios.

3 Does not include ore imported free of duty for treatment in bonded works for export.
4 Estimate.
5 Duties for calendar year 1910 not available.

128898—1942

I. GENERAL INFORMATION,

DESCRIPTION.

Ores containing zinc can be divided into the following classes: 1

(1) Calamine or carbonate ore and concentrate containing approximately 40 per cent zinc and only very small amounts of other metallic elements.?

(2) Blende or sulphide ores and concentrate containing approximately 60 per cent zinc and only very small amounts of other metallic elements.

(3) Sulphide ores and concentrates produced in the Rocky Mountain districts averaging between 38 and 50 per cent zinc and with relatively high content of iron and sulphur.

(4) Complex sulphide ores containing up to 35 per cent zinc but averaging about 20 to 25 per cent of zinc associated with other metals besides iron and including lead or copper.

Ores of the first two classes rarely have any precious metal values. Those of class 3 usually contain a certain amount of precious metal, while those of class 4 almost invariably do so. The first three classes of ore are accepted by zinc smelters for the production of spelter. The fourth class is a middling product that can usually be sold only to a concentrating plant for further mechanical separation. More recently a market has begun to develop for such ores for use in making electrolytic zinc, and for igneous concentration.

In the Missouri ore schedules only two classes of ores are distinguished. Blende is sold on the basis of a 60 per cent zinc content, while calamine is sold on a basis of 40 per cent. Such high concentration is impossible at most of the Western mines, so there are special schedules for ores containing large amounts of iron sulphides. In general, a product that contains less than 35 per cent of zinc can not be sold to the smelteries. Most of the material of this nature that is marketed is a middling product obtained in concentrating more or less complex ores. There are companies that make a business of buying and treating such material by processes described later. Few of these establishments operate on a purely custom basis, charging a fixed rate per ton. Most of them purchase the ore outright, covering metal losses and their expenses (and profits) in a complicated schedule of discounts and payments.

In addition to these common ores, mention should be made of the unusual varieties of zinc minerals found in important quantities only at Franklin Furnace, New Jersey. This deposit, however, is unique in the character of its ores and is operated by only one company. Much of this ore is used for the production of zinc oxide, and the remainder is used for the production of zinc metal of exceptional purity. It is, therefore, in a class by itself and is not a factor in the general consideration of the industry.

2 The term "calamine” as used by the mineralogist defines only the hydrous silicate. In Europe, how ever, it applies to all silicates and carbonates and also includes a zinc crust found in blast furnaces that treat zincy charges. The term found a degree of acceptance in the United States as a general term applying to all oxidized ores (except zincite and franklinite) and including carbonate. This double significance resulted in much tariff litigation in 1906–1909.

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COMPLEX ORES.

All ores containing zinc, even when this metal is present in fairly large amount, are not classed or useful as “zinc ores." The zinc minerals are common associates of the ores of other metals, notably lead and copper. In all ores except those mined chiefly for their zinc content, the presence of zinc is deleterious. Smelters invariably penalize ores that contain zinc in excess of 10 per cent, and sometimes even less amounts are penalized. Zinc is a highly undesirable element in a blast furnace charge, invariably resulting in lowered recoveries as well as increased difficulty of operating:

Even if the zinc minerals can be separated by a preliminary mechanical or chemical treatment and a product made and sold as zinc concentrate, the other values of an ore are almost invariably depreciated by the accompanying zinc. This statement will hold generally true for any case where a product containing not over 30 per cent zinc can be made by ordinary methods of wet concentration. The field of economic recoveries from complex zinc ores has been widened a little by the comparatively recent success of selective or preferential flotation, but even this process involves additional treatment expense and overlapping losses that materially reduce the theoretical value of the ore as calculated from its combined metal content.

The cost of separating a salable zinc product from a typical complex middling product will range from $1.50 to $3 per ton. Some of the zinc mineral will invariably pass into the lead (or copper) products and is thereby not only lost but may even result in a penalty being charged against the lead" (or copper) concentrate. A variable amount of gold, silver, lead, and copper will be retained in the zinc concentrate and as will be shown later the value of other metals in zinc concentrates is heavily discounted. In addition to the lead (or copper) concentrates and the zinc concentrates, frequently a third sulphide or "iron” product is made which also contains all the valuable metals in greater or less amount and can rarely be sold advantageously except in certain districts where it can be used as a source of sulphuric acid.

All the above losses are in addition to those that accompany the initial concentrating of the mine ore with its inevitable tailing losses.

USES.

The essential uses of zinc are: In brass (an indispensable material in modern industry); in galvanizing; as structural sheet; and in the desilverization of lead bullion. The consumption is greatest in galvanizing A wide list of miscellaneous uses for zinc includes the chemical, rubber, paint, electrical, and metal industries, and medicine.

The chief use of zinc ores is of course for the manufacture of spelter, but an increasingly large amount is used in the United States for the direct manufacture of zinc oxide and other pigments ? and zinc dust.2 Blende is an important source of sulphuric acid, a large tonnage of which is recovered as a by-product in the making of spelter.

1

1 Report on spelter in the files of the Tariff Commission. 2 Reports in the files of the Tariff Commission.

COUNTRIES OF LARGEST PRODUCTION.

The world's production of zinc has fully trebled in the last 25 years. The United States is undoubtedly the largest producer of zinc ore as well as of spelter in the world to-day. Before the outbreak of the European War, this position was held by Germany, but the enormous strides made by the United States in 1915–1917 forced Germany into second place. Belgium, which prior to the war was the third largest spelter producing country, has not been a large producer of ore for many years. Similarly France and Great Britain, although important smelting countries, are not important as zinc ore producing regions. Japan is another country that is more important in the smelting business than as an ore producer.

Data collected by the Bureau of Mines show that the order of production of the various zinc ore producing countries in 1913 was as follows:

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The productions of the more important zinc-mining countries in 1917. were in the following approximate order: United States, Germany, Australia, Mexico, Canada, Italy, Japan, Spain, Siberia, and India. Probably the order at the present writing is not greatly different, but it should be noted that the boundaries of Germany as now defined by the peace treaty transfer the greater part of the zinc resources (as well as reduction works) of that country to the new state of Poland.

DOMESTIC PRODUCTION.

The United States has increased its proportion of the world's output from only about 20 per cent in the early nineties to about 60 per cent during the war period. Since the world output also has largely increased in this time, this percentage increase involved a much greater absolute expansion than would appear from the above figures. The output of domestic zinc mines in 1917 was eight times the annual output of 25 years ago. Most of the growth took place since 1914, during which time the domestic production increased over 50 per cent,

1 According to M. F. Chase (Am. Metal Market and Daily Iron and Steel Report, June 10, 1919) only 840 tons of the 488,730 tons of ore smelted in Belgium in 1913 were produced in that country.

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