A concentration by this dry method on a small scale gave the following results:

Results of dry concentration by sifting with previous rubbing.

Concentration ratio-ore: concentrate-3.73 : 1; extraction V2O5=50.85 per cent; extraction U,O=52.85 per. cent.

Care must be taken in crushing the ore for either wet or dry concentration that little, if any, of the dustlike material is lost. Dust chambers should be attached to the crushers, or the latter should have air-tight casings and the material should not be removed until the dust has settled.

COST OF CONCENTRATION.

The factors to be considered in a calculation of the cost of concentrating the ore by a wet method are:

1. Cost of concentration:

(a) Water supply.

(b) Cutting wood for fuel for power and drying (or cost of gasoline if that is used for fuel).

(c) Hauling of fuel or gasoline.

(d) Wages for concentrator men.

2. Amortization of equipment for concentration (pro rata of tonnage of material treated per annum for such equipment and for management).

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Two men, at $3 a day each, should be able to operate a small plant. The cost of water supply should not exceed $2 a day. The cutting of fuel or cost of gasoline should not be more than $2 to $2.50 a day. The hauling of the fuel would probably cost $1.50 a day. On an average, from 10 tons of ore mined only 1 ton of ore with a content of over 2 per cent UO, is obtained by hand sorting. From the other 9 tons, thrown on the dump, about 5 tons of low-grade ore can be separated for concentration. Assume that such low-grade ore contains, on an average, about 1 per cent U2O and 1.5 per cent V2O,. With a concentration ratio of 10 to 1, half a ton of shipping ore should be obtained. The total extraction of mineral by a wet method should be about 50 per cent, and the

grade of the material obtained would therefore be fairly high. In an actual test on such a low-grade ore the percentage of U2O, in the concentrate was found to be about 4.5. This should of course command a proportionately higher price.

The cost of concentration by the dry process is approximately the same, less the cost of the water supply.

The cost of concentration, including ample charges for amortization and for management, should not exceed $20 per ton of concentrate. These figures are conservative and probably the ores can be concentrated more cheaply.

The average cost of mining with present methods at the rate of 10 tons of ore a day with 6 men and the hand sorting done by the foreman is about $30 per ton of shipping ore. This figure does not take into account the powder used in blasting, the wear of tools, etc. If the low-grade ore is utilized by means of concentration, the expense of mining is thereby increased little, if any, and only the additional cost for the concentration has to be taken into consideration, the charges for sacking and hauling the concentrate to the station being the same as for a ton of ordinary ore.

From the above it will be seen that through utilizing the low-grade ores the average tonnage per annum could be increased 50 per cent with little extra expense. But as the uranium and vanadium content of the concentrate would be at least double that of the average ores shipped, the total production of uranium and vanadium from these ores would be doubled. For various reasons it is hardly to be expected that all of the waste material can be utilized, and therefore such a large increase will probably never be actually obtained. Perhaps several of the operators could combine and install an equipment for mechanical concentration and treat their low-grade ores in a central plant, especially where several operators are in the same district and the claims are near each other. With such a plant in use the production of marketable ore at the present rate of mining could be increased by about one-half without increasing the cost of mining and with only the additional expense of concentration. This increase can be obtained by treating material that hitherto has been lost.

The assumption, which has been made by many of the dealers, that by concentration a large part of the radium content of the ore would be lost, is entirely without foundation, as no such losses of radium in the concentrate can occur from any mechanical treatment of the ore. This has been proved by our tests of the concentrates (pp. 37, 39). Undoubtedly the statement has reference to chemical concentration, in which, of course, such losses might occur.

POSSIBILITY OF CHEMICAL TREATMENT.

A chemical treatment of the low-grade carnotite ores at or near the mine would undoubtedly be better and a larger extraction could be obtained were it not that the present high cost of hauling chemicals to the mine prohibits such treatment. In addition, the average operator could not obtain such labor as would be necessary in a chemical process. The deposits worked by the smaller miners are scattered, and their probable output is too uncertain to justify the erection of even a small chemical plant. This statement does not apply to a chemical plant conveniently situated for the treatment of custom ores.

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GENERAL STATEMENT.

The possibility of a continuous supply of carnotite ores in the future is naturally of great interest. In the Utah fields, as already stated, the ores are generally low in uranium, although occasional small pockets of high-grade ore are found. Some of these deposits have the advantage of short hauls; others, such as those at Table Mountain, have as long a haul as most of the ores taken out of Paradox Valley. Since the present demand requires an ore containing at least 2 per cent UO, the operators in the Utah fields have to do such careful sorting that a large proportion of the uranium ore is wasted. There is therefore, as already explained, great need of a concentration method, or methods, that can be used by an operator at his own camp, or at least by a group of operators working nearby claims. In this way not only would the low-grade uranium ores be made available but also the vanadium ores that contain too little vanadium to be worth marketing under present conditions. It is quite possible that such ores may be so concentrated that the concentrates can be handled for their vanadium content alone, even though they contain too little uranium to warrant their being classified as uranium ores.

In Paradox Valley at present little difficulty is experienced in obtaining 2 per cent ore by careful sorting, and a fair amount of ore carrying 3 per cent or even more has been mined during the past year; but there has been much waste in the sorting of this ore and more low-grade material has been left in the mines untouched. This is particularly true in Saucer Basin and at certain points on the south side of East Paradox Valley. It is difficult to state just how much ore suitable for concentration but not rich enough to ship on the present basis is available in the Paradox and surrounding districts. It is certain, however, that there is enough already in sight to double the output for several years to come, if it could all be made marketable.

As this is hardly possible a 50 per cent increase is probably all that could be expected under the most favorable conditions.

The present policy, which is really necessary on account of the cost of production, of shipping only ore containing 2 or 3 per cent UO, is bound to have a far-reaching result. The buyers are urging the shipment of even higher-grade ore and are offering a bonus for it. Hence the tendency has been to raise rather than to lower the minimum percentage, a correspondingly larger waste resulting. Although some of the pockets in Paradox Valley are large, a number of the largest have been worked out within the past two years. The output of 2 per cent ore may be as large for several years to come as it has been during the past year, and may even increase for a while, but after a few years the production of high-grade material will inevitably decline. The buyers will then either have to accept a smaller output or handle low-grade material. New pockets will naturally be opened from time to time and a certain percentage of high-grade material will be available for many years to come, but it is extremely important that methods be devised for utilizing at least some of the low-grade material now being thrown on the dump or left in the mine.

The United States possesses unique deposits in these carnotite ores. They constitute at present the largest known supply of radium-bearing minerals in the world. With the exception of the ore mined and utilized by two firms, practically every pound is shipped abroad. Up to the present very little interest has been shown by Americans in these deposits, which may not be duplicated in so far as quantity goes in any part of the world.

The only other large deposits of uranium-bearing ores known are those in Austria. They are considered of such importance that the Austrian Government has taken entire charge of them. The output from the carnotite fields of this country is much larger than that from the Austrian mines and is likely to continue larger for some time to come, but the ore should be mined with minimum waste and the industry should yield a maximum profit to this country. There is little danger that the amount of ore mined per annum will increase materially. The long hauls and the scattered occurrence of the deposits make it difficult to largely increase the production in any one year. Such an increase can be accomplished only by utilization of the low-grade ores.

A word of warning may be added at this point. The fact that carnotite and its associated ores are found on a claim does not necessarily mean that such a claim is worth even the assessment work that has been expended on it. Already one company is making extravagant statements in its advertisements, and others may follow it.

PITCHBLENDE DEPOSITS.

DESCRIPTION OF DEPOSITS IN THE UNITED STATES.

Pitchblende has been found in the following localities in the United States: Feldspar quarry, at Middletown, Conn., in large octahedrons; in Hall's quarry, at Glastonbury, Branchville, Conn., in a pegmatite vein and usually embedded in albite; at Marietta, S. C.; in the Baringer Hill district, Llano County, Tex.; in the Bald Mountain district, Black Hills, S. Dak.; in Gilpin County, Colo.; and in Mitchell County, N. C.,

NORTH CAROLINA DEPOSITS.

In Mitchell County, N. C., small quantities occur near Penland in the quartz and feldspar mines. The mineral is usually associated with quartz, but in places with orthoclase feldspar, and still more infrequently with albite. Its presence is usually indicated by a dullgreen stain on the quartz or spar, although such stains do not invariably mean that ore is present. The pitchblende from near Penland is usually high grade and is often associated with yellow gummite. In probably the best mine only 50 pounds have been found in 11⁄2 years, so that as yet the mining of these deposits can not be considered a commercial enterprise. The ore is usually sold in small quantities as museum specimens at specimen prices.

COLORADO DEPOSITS.

In Gilpin County, near Central City, Colo., are five mines that have produced pitchblende, namely, the Kirk, the Wood, the German, the Belcher, and the Calhoun. These mines are all within about 2 miles of Central City and are situated on or very close to Quartz Hill, at an altitude of 9,500 feet. The Kirk, Belcher, and German mines are close together on the hill; the Wood and Calhoun are in the valley.

These mines were originally gold mines and until recently have been worked mainly for gold. Gilpin County is the oldest mining district in the State of Colorado, and it was here that the first stamp mills and smelters in Colorado were built. The ores near the surface are mainly free-milling; lower down they change to sulphides. The veins are persistent, but the quality of ore often varies considerably within a short distance.

KIRK MINE.

The original workings of the Kirk mine are about 100 feet deep. The majority of these have been filled up. In this manner the