Chapter X: Molybdenum

BY R. B. MOORE

USES OF MOLYBDENUM

Molybdenum is used in the manufacture of ferro-alloys for making steel. As wire, it is used for supporting the filament in incandescent electric lamps. The wire is also employed for winding electric resistance furnaces and for this use has proved cheaper and better than platinum because of the quicker heating and higher temperatures attainable. The metal has been successfully substituted for platinum and for platinum-iridium in electric contact-making devices. Molybdenum compounds are used in chemistry, particularly ammonium molybdate for the determination of phosphorus. Fast colors in a variety of shades may be produced on leather by employing molybdenum tannate in conjunction with logwood extracts. It has been employed for color glazes in porcelain and in coloring silks and rubber.

The addition of molybdenum to steel increases the elastic limit without diminishing the ductility. Molybdenum can be substituted for a certain percentage of tungsten in high-speed steel, as a rule one part of molybdenum taking the place of two to three parts of tungsten.

GEOLOGICAL AND GEOGRAPHICAL DISTRIBUTION

Up to about 1916, practically all of the molybdenite concentrates produced came from Queensland, New South Wales, and Norway. Shortly after the opening of the war, interest was shown in the production of molybdenite in Canada, principally in the provinces of Ontario and British Columbia. During 1917 and 1918 there was a great deal of interest in the United States in molybdenum ores, and at the present time this country can probably produce molybdenite concentrates in quantity equaling if not exceeding the rest of the world put together. Some molybdenum is produced by Spain and Peru.

=Australia and Norway.=--The first official record of a production of molybdenite in _Queensland_ was in 1900, when the output amounted to 12.3 short tons of high-grade material. The production gradually rose to 119 tons in 1906, and has not varied materially since that date, although the selling prices for concentrates increased considerably. The bulk of the material was mined at Wolfram Camp, in the Chillagoe field, 120 miles southwest of Cairns, in Northern Queensland. The mines at Bamford, in the same field, are credited with a small output. With the molybdenite ores are bismuth-tungsten ores, so that all three metals are produced.

The production of molybdenite was first reported in _New South Wales_ in 1902; in that year the output was 17 short tons. The total output to the end of 1914 was 498 short tons, valued at $264,000. The chief producing molybdenite mines are at Whipstick, in the Pambula division, at Kingsgate, in the Glenn Innes division, and near Deepwater, in the Deepwater division. Molybdenite is also being produced at Rocky River, in the Tantafield division, and in the Bathhurst division. The production at all of these localities has not been large--in no one year exceeding 100 tons of concentrates.

In _Norway_, the production of high-grade molybdenite concentrates has averaged about 30 tons per annum since 1902. In 1906, an output of 1,129 short tons was reported. This probably refers to ore mined and not to concentrates produced.

The chief molybdenite districts in Norway are the provinces of Lister, Mandal, and Nedenes, on the extreme southern end of the peninsula. The district of Fjotland, in the former province, is probably richer in molybdenite than any yet discovered in Norway. A mine at Knaben, in this district, has been the largest and probably the only successful producer in Norway. This mine, owned by George G. Blackwell & Sons, of Liverpool, England,[94] has made an average output of about 25 short tons per annum.

[94] Reported taken over by a Norwegian company. U. S. Commerce
Reports, September 24, 1918.

TABLE 33.--PRODUCTION OF MOLYBDENITE IN QUEENSLAND, NEW SOUTH WALES AND NORWAY

----+----------------+----------------+----------------
| Queensland |New South Wales | Norway
+------+---------+------+---------+------+---------
|Weight| |Weight| |Weight|
|(short| Value |(short| Value |(short| Value
Year| tons)|(dollars)| tons)|(dollars)| tons)|(dollars)
----+------+---------+------+---------+------+---------
1902| 45.9| 26,770 | 16.8| 8,960 | 22| 16,100
1903| 26.9| 10,220 | 32.5| 21,960 | 34| 21,400
1904| 23.6| 13,010 | 28.3| 13,270 | 33| 17,400
1905| 70.8| 41,340 | 21.7| 12,200 | 51| 16,300
1906| 118.9| 74,330 | 36.6| 23,350 | 1,129| 14,200
1907| 74.0| 41,080 | 24.2| 17,340 | 33| 12,900
1908| 98.7| 44,960 | 9.5| 4,520 | 39| 13,400
1909| 103.9| 45,120 | 31.5| 15,810 | 33| 12,100
1910| 118.6| 58,640 | 53.2| 27,580 | |
1911| 111.4| 64,610 | 23.1| 12,610 | 2| 800
1912| 114.6| 84,420 | 63.3| 18,030 | 23| 5,400
1913| 74.3| 92,460 | 88.3| 33,100 | 13| 3,200
1914| 87.1| 185,830 | 68.8| 55,720 | |
----+------+---------+------+---------+------+---------

The production of molybdenite in Queensland, New South Wales and Norway, by years, is shown in the preceding table.

Figures for more recent years indicate the total production in Australia of about 330 short tons per annum and 110 short tons in Norway in 1916. In 1917 the output in Norway was three times the 1916 figures.

=North America.=--As already stated, the chief molybdenite deposits in _Canada_ are in the provinces of Ontario and British Columbia. They are low grade and of course need concentration. The Canadian and British governments have been much interested in the concentration of these ores and the Canadian government has a mill engaged in experimental work and in commercial concentration. The Department of Mines has spent a good deal of time in experimentation, believing that molybdenite has an important future in metallurgy.

The production in 1917 was about 80 short tons of high-grade concentrates and was undoubtedly larger in 1918.

Canada when properly prospected may produce a good deal more molybdenite than now.

In the _United States_ are a very large number of small molybdenum deposits, scattered over the western states from Washington to Arizona and from Colorado to California. There are two common minerals--molybdenite, or molybdenum sulphide, and wulfenite, or lead molybdate. Generally speaking, molybdenite is found in the northern states, and wulfenite in the southern states, but this rule is not without exception. In Arizona and New Mexico, the principal mineral is wulfenite, but there are some fairly large deposits of molybdenite, probably the best being at the Leviathan mines, in Copper Canyon, Mohave County, Arizona. This is the only molybdenite deposit that is being worked in New Mexico or Arizona. It is in the Cedar Valley mining district about three miles southeast of Copperville and about 25 miles east of Yucca. This ore carries a good deal of copper, as well as small traces of gold and silver. Some analyses have shown 2 or 3 per cent. MoS₂ and 1¹⁄₂ to 2 per cent. copper with 0.02 ounce of gold and 1 to 4 ounces of silver per ton. The percentage of molybdenite is undoubtedly above the average, which does not exceed 1 per cent. The country rock is medium-grained gray granite, consisting of quartz, feldspar, biotite, muscovite and small amounts of other accessory minerals, such as zircon and apatite. The company has erected a mill and has succeeded in making a satisfactory separation of the copper from the molybdenite.

The largest possibilities in Arizona and New Mexico are in mining wulfenite. This mineral is widely scattered over these two states, especially Arizona, and is, to a great extent, associated with vanadinite. One of the greatest difficulties in concentrating wulfenite has been the separation from vanadinite. The Bureau of Mines has worked on this problem for some time with partial success.

The most important deposit of wulfenite is at the Mammoth and Collins mines, in Pinal County. They were originally gold mines, and when the value of molybdenum became evident, Colonel Randolph, owner of the Mammoth mine, decided that it would be worth while to run the tailings dump for wulfenite. He converted his mill to this purpose, and not only ran the Mammoth dump but also the dump at the old Yuma mine, in Pima county. The total amount of concentrates produced by Colonel Randolph and others in the vicinity during the three years 1916 to 1918 are probably represented by 1,000 to 1,200 tons of wulfenite concentrates. While these operations were going on, they represented practically the only production of molybdenum concentrates in this country except on a very small scale. One other operating company is the Rowley Copper Mines Co., Gila Bend, Arizona, the ore being wulfenite and the principal impurity barite. The company has succeeded in making satisfactory concentrates, which carry, however, a considerable amount of barite. The Golden, Colo., station of the Bureau of Mines has run some tests on this concentrate and has made a partial separation of the barite and wulfenite.

Molybdenite is found in a considerable number of places in Colorado, Montana, Washington, Nevada, Utah, Texas and other western and northwestern states, but the largest occurrence is in Colorado. Generally speaking, the individual deposits in the West are not large enough to warrant the building of a mill for any one of them, and as the deposits are widely scattered, it is difficult to find a place where a custom mill could obtain a sufficient amount of ore. This is one of the chief difficulties in producing a large tonnage of molybdenite concentrates, outside of Colorado.

Probably the largest deposits of molybdenite in the world are at Climax, Colorado. These deposits are on the southwestern slope of Bartlett Mountain, Summit County, about 15 miles from Leadville. Outcrops are practically continuous across the whole length of the mountain and at places are one hundred to two hundred feet thick. The ore is rather granular and not flaky molybdenite, the average grade running about 8 per cent. MoS₂.

There are two operating companies, the Climax Molybdenum Co., a subsidiary of the American Metal Co., of New York and Denver, and the Molybdenum Products Co., of Denver. Both of these companies have erected mills having daily capacities of 200 tons. The mill of the American Metal Co. started continuous operation about March, 1918, and that of the other company was completed shortly afterwards. Both companies claim that they can enlarge the capacity at short notice. The writer was in the mine of the American Metal Co. Evidently a considerable part of the mountain is molybdenite, and without doubt, a very large tonnage can be produced. The Jackling interests recently acquired the adjoining properties owned by the Pingree Mines Co., but in 1918 had not built a mill or carried out any serious development work.

Another very large group of deposits of molybdenite lies near Empire, Clear Creek County, Colorado, on the eastern slope of Red Mountain, at an altitude of about 11,000 to 12,000 feet. The deposits are 14 miles from the Empire station of the Colorado & Southern Railroad and are owned by the Primos Chemical Co., of Primos, Pennsylvania. The ore-bearing bodies consist of three veins of low-grade ore. The ore zone, that is, the ground included between the footwall of Vein No. 1 and the hanging wall of Vein No. 3 where cut by the tunnel, is about 200 feet wide. The veins vary greatly in width and are not particularly well defined, thin veinlets and stringers of ore running into the walls. The Primos Chemical Co. has worked these mines off and on for several years. About three years ago it built a mill near the mine, but production has been rather intermittent. This company has probably used all of its concentrates for making ferromolybdenum at its own works in Primos, Pennsylvania.

A small mill has been erected at Pitkin, Colorado, in connection with the mine at that place owned by the Pennsylvania Molybdenum Mines Co., of Johnstown, Pennsylvania. A number of other deposits of considerable interest are found in Colorado, especially around Breckenridge, Summit County. Here the pegmatite veins consist largely of muscovite and quartz, with some feldspar, and carry biotite, chalcopyrite and accessory minerals. The difficulty here is to separate the molybdenum from the copper minerals and also from the mica, most of which floats with the molybdenite.

Most of the developed molybdenum deposits of _Mexico_ are in the State of Sonora. In the Sahuaripa district of eastern Sonora, the mineral occurs with scheelite in rich pockets containing very large pieces of pure mineral. Some molybdenum ore has been shipped from the Montezuma copper district to the Empire Smelting & Refining Co., of Deming, New Mexico. Molybdenum is reported in several other Sonora localities. Near Coyame and Marquez, northeastern Chihuahua, the mines of the Compañia Minera Aurora y Anexas produce molybdenum ore. Wulfenite is found abundantly with the lead ore of the Cuchillo Parado mine in the same district. The Jibosa copper mine of the American Smelters Securities Co., near Jimenez, Chihuahua, seems to carry considerable oxide of molybdenum, molybdite. It is not commercial at present.

Molybdenite deposits are also reported in the states of Sinaloa, Oaxaca, Hidalgo, and Jalisco.

RESERVES

As the production of molybdenum ores in the past in all countries has been relatively small, probably none of the deposits have been worked out and an increased output can be obtained. This applies particularly to the United States. All of the work that has been done so far has been on an experimental basis, and possibly the only mine whose tonnage will be decreased by past production is the Mammoth mine, near Mammoth, Arizona, and there is no certainty that this mine can not continue to produce as much for some time in the future as it did during its period of operation. Just what production can be obtained in the United States is somewhat uncertain, but it is probable that the deposits at Climax, Colorado, will yield at least one thousand tons of ore a day for several years and possibly for a good many years. The deposits of the Primos Chemical Co. near Empire, Colorado, are also extensive and should give a large output for some time to come. The rest of the deposits mentioned are small compared with these two, but the total production of all of them might be large, were a steady market assured and custom mills erected.

TREATMENT OF ORES

In concentrating wulfenite ores some form of table concentration, with the addition of slimers, is generally used. The metallurgical treatment of the concentrates varies and is still very much in the experimental stage. There is opportunity for the development of a process that will give the patentee a considerable advantage over competitors. The Bureau of Mines has been working on this problem and has recently devised a method that seems to be as efficient as any other and possibly has some additional advantages.

In the treatment of molybdenite the same methods are almost universally used. First the ore is crushed to the required fineness and the molybdenite is separated by flotation, largely oil flotation. The metallurgy of the concentrate, now more or less standardized, involves roasting the concentrate to the oxide and treating this oxide in an electric furnace for the production of ferromolybdenum. With small improvements, this practice is likely to be maintained for some time to come.

POLITICAL CONTROL

The political control of the molybdenum deposits of the world is determined by the geographical location. At present most of the known deposits are controlled by the United States and Great Britain, the latter controlling those in Canada and Australia. The British and Canadian governments actually have a government mill in Canada.

COMMERCIAL CONTROL

The Knaben mines, in Fjotland, the most famous and probably the only successful molybdenum mines in Norway, were acquired in 1905 by an English company, the Blackwell Developing Corporation. Later a newly organized Norwegian company, with head office in Christiania, took over the mines at a price of 2,500,000 crowns.

In _Mexico_ the large molybdenum deposit in the Sahuaripa district of eastern Sonora is owned by George Fast, of Douglas, Arizona. The Lucky Tiger-Combination Gold Mining Co., of Kansas City, Mo., (American) owns the deposits in the Montezuma district. Another American company has acquired deposits near Poza, Sonora, about 20 miles north of Hermosillo. A deposit located 35 miles from the port of Topolabampo, northwestern Sinaloa, is owned by an American. The Compañia Minera Aurora y Anexas, operating molybdenum mines near Coyame and Marquez, northeastern Chihuahua, is owned by the Madero estate. The ore has been shipped to Leonard Worcester, El Paso, Texas, agent for the estate and also purchaser for L. Vogelstein & Co., New York, formerly a branch of the German metals combine.

In the _United States_, during the war the claim was made a number of times, both privately and in the press, that German interests were trying to obtain control of the molybdenum deposits of the country. This was due to the fact that the American Metal Co., which operates at Climax, Colorado, as the Climax Molybdenum Co., and which has some other molybdenum deposits, was formerly controlled by German interests. It is true that the majority of the stock of the American Metal Co. was owned in Germany, but Mr. Palmer, the Alien Property Custodian, took charge of this stock, and the affairs of the American Metal Co. were readjusted to changed conditions. The principal stockholders of the Primos Chemical Co. were four brothers by the name of Boericke. Before the war they had strong German connections, but outside of their deposits at Empire they made no special effort to get large molybdenum holdings in this country and did not seek to get a combination of any of the operating companies. The Primos Chemical Co. has since 1919 been taken over by the Vanadium Products Corporation, affiliated with the Bethlehem Steel Corporation. The Molybdenum Products Co., Denver, Colorado, which owns a part of the molybdenum deposit on the slope of Bartlett Mountain, near Climax, and operates a 200-ton mill, is a subsidiary of E. J. Longyear Co., exploring engineers, of Minneapolis, Minnesota. Both companies are owned by American stockholders.

In _Canada_ and _Australia_ it is certain that no one large interest has control, as the ore comes from a number of more or less independent small mines.

A large number of patents have been issued in connection with the concentration and metallurgy of molybdenum. None of these is vital to production; most are valueless, and even those that have a distinct value do not necessarily give control to the owner of the patents or secret processes.

In order to insure a steady demand for molybdenum, the prime requisite is a definite knowledge of the properties and uses of molybdenum steel. In the past this has been lacking, and at present it is not possessed by the majority of operators and steel makers. Europe should assist materially in supplying this deficiency. Molybdenum steel at the present time is in the same position as vanadium steel was a number of years ago--it is on trial. This uncertainty caused a very decided slump in the demand for molybdenum concentrates in the spring of 1918. A control of molybdenum is more likely to come through the manufacture of molybdenum steel than through processes connected with the production of concentrates or ferromolybdenum.

POSITION OF LEADING COMMERCIAL NATIONS

At present the _United States_ has the largest potential supply of molybdenum ores of any country in the world. In addition it has three of the largest and most modern mills that are handling ore from any molybdenum deposit. It is in a favorable position to equal or surpass, for some time, any other country, in output of molybdenum concentrates.

Before the war _Great Britain_, through political control of the Australian and Canadian deposits, was the world’s leading producer. Some molybdenum came from _Norway_, but the amount was small as compared to the output of Australia, Norway producing in 1913 only 13 short tons and Australia 162.6. In both Canada and Australia the known deposits have not been worked to capacity and new deposits will probably be discovered with proper prospecting, so that the future molybdenum production under British control promises to increase. The Canadian and British governments are much interested in the development of the molybdenum resources of the dominion.

_France_ is entirely dependent upon England and the United States, although it might be able to get a small amount of concentrates direct from Norway.

_Germany_ was much interested in molybdenum before the war. During the war it probably did not import any molybdenum concentrates at all, and as the world production before that time was small it is not likely that there was any reserve on hand in the empire in 1919.

_Japan_ has no molybdenum deposits as far as is known, and probably is not specially interested at present in the use of this metal.

The distribution of the chief molybdenum deposits of the world is shown in Plate VII.

SUMMARY

Molybdenum commands attention because of its growing importance as a steel alloy metal. Although the metallurgy and properties of molybdenum steels are not thoroughly understood and their use is not widespread, especially in this country, accumulating evidence indicates that molybdenum will eventually become one of the common alloy metals. It is used in the form of wire as supports for incandescent light filaments and in electrical apparatus, and may become essential in the manufacture of special steels. It cannot be easily replaced in chemistry, and for its other applications it is better and cheaper than other materials.

Up to 1915 practically all of the molybdenum produced came from Queensland, New South Wales, and Norway. At present more important deposits are being developed in Ontario, Quebec, and British Columbia, Canada, and in Colorado, Arizona, New Mexico, and other western states. The mineral is widely distributed and the discovery of additional deposits is likely if the demand is sufficient to encourage prospecting. The United States has deposits large enough to meet all domestic needs and also to produce a surplus for export. Some molybdenum is obtained from Mexico, Peru, and Spain, but the United States, Great Britain (Canada and Australia), and Norway control the important deposits.

The largest molybdenum deposit in the United States, located at Climax, Colorado, is owned by the Climax Molybdenum Co., a subsidiary of the American Metal Co. (formerly German), and by the Molybdenum Products Co., of Denver, an American company. Other deposits in Colorado are owned by the Primos Chemical Co., a company that had strong German connections before the war, but has been taken over by the Vanadium Products Corporation, an American company. Other producing deposits of the United States are owned by American citizens.

The Knaben mines, the most important in Norway, have been owned since 1905 by an English company, but, according to a report, they have been acquired by a Norwegian company. A number of the deposits of northern Mexico are owned by Americans. Others are owned by the Madero estate (Mexican). The Canadian and Australian deposits are controlled by small, independent operators. Both the United States and Great Britain have ample supplies of molybdenum; France produces none and is dependent upon other countries; Germany, which was much interested in molybdenum before the war, probably has no large stocks on hand.