Mineral Processing Engineering

Mining Geology Book

Succession of Minerals and Temperatures of Formation in Ore Deposits of Magmatic Affiliations. The paper presents data accepted by many geochemists and geologists regarding the succession of minerals and the temperatures of formation in ore deposits affiliated with igneous rocks It also presents the individual views of the author on the composition of the solutions that were active and on the mode of deposition He does not regard these views as speculations or hypotheses but as forming a well motivated and consistent theory It is not certain, however, that all investigators will subscribe to them The mining engineer may not always be interested in the field of stability and temperature of origin in the mineralogy of ore deposits, but he certainly is interested in the succession of minerals because this has a definite bearing on the understanding of the ores and on the best processes of extraction The author, therefore, summarizes in plain language the principal features of succession as shown in metallic ores.mining_geology_book

Fissility he considers to be a “structure in rocks by virtue of which they are already separated into parallel laminae.” Fissility may be regarded as a development of the

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Assaying for Silver and Gold

From time immemorial the methods of assaying any materials for silver and gold were in reality nothing but laboratory smelting methods. The writer arrived in Butte, Mont., he found that these metals, contained in copper bullion, were still determined by the all-fire assay, both in the same charge. There seems to be no record as to when and where the so-called combination method (dissolving the copper in nitric acid and precipitating the silver as chloride, etc.) was first introduced; but in the early nineties of the past century it became evident that for the sake of accuracy of the gold assay this metal must be determined by the all-fire method which, on the other hand, was quite unsatisfactory for silver. The combination method became the standard method for silver and the all-fire the standard for gold. From that time on probably most assayers were longing for a reliable single method for both metals, since the simplicity of the combination method, with its accurate results for silver, contrasted strongly with the unchemical, tedious and expensive all-fire method for gold.

To many, the comparative cost of the all-fire and sulphuric-acid assay-methods may be of interest. For the Anaconda laboratory, of Perth Amboy, it

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Froth Flotation Principles

The Froth Flotation Machine and its operating principles are universally used for all types of flotation problems. This machine finds a wide acceptance due to its flexibility in construction, which allows the machine to be adjusted to handle pulps with divergent physical characteristics, as well as the common and intricate metallurgical problems which confront the present day operator.

The Froth Flotation Machine is so designed that it will do a most acceptable job for coarse as well as fine flotation. The selectivity and flexibility are outstanding features and these, coupled with low operating and maintenance costs, makes the “Sub-A” synonymous with the word FLOTATION.

The tool “Floatation” since its general introduction some thirty years ago, has made rapid strides until it is now used for concentrating more ores than any other process. The “Sub-A” itself came into being in 1927 and in the intervening years its development has kept pace with the advancing technique in the ever-widening field of ore dressing. Flotation and the “Sub-A” are now major factors in the concentration of:

  1. Free metal ores;
  2. Sulphide ores;
  3. Metallic oxides;
  4. Non-sulphide or non-metallic ores, and in addition, progress is being made with
  5. Industrial applications.

The following resume gives a brief insight into the

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Copper Bullion Assay

Someone some time ago remarked that some chemists still insist on telling us how to determine copper by the electrolytic method. The writer must confess that he believes that everything is not known definitely as yet as to how the exact amount of copper is determined in such material as purest commercial electrolytic copper. Some of us are not yet convinced that the pure copper atom is at all times deposited from an acid solution and that no oxygen or hydrogen will, under certain conditions, accompany it. Difficulties with impurer material are frequent, but erroneous results are not always apparent, since these do not speak so readily for themselves as those in the first case. By this is meant that if a chemist finds 100 per cent, of copper in electrolytic copper it is pretty certain that he perceives the result to be wrong, while if he finds 0.1 per cent, of copper too much in a very impure material he is far more likely to be unconscious of his error. These, in a wide experience, are frequent happenings and the writer has always looked with interest to publications on this subject. In turn, he feels justified in giving

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Applied Mining Geology

The geologic notes are taken as soon as possible after the ground is broken so that any mistake in the mining may be corrected at once, or any particularly advantageous procedure may be suggested before any useless work is done. Taking the notes underground is a comparatively simple matter, but a few necessary precautions may be pointed out. The essential to success is that the notes shall show exactly what geological facts are disclosed. The observer must discriminate carefully between important and unimportant exposures in making the record, especially as regards the relation between veins and stringers, between faults and minor slips, or between the characteristics of veins of different ages. A simple color scheme has been adopted for making this record. Red pencils are used to indicate vein filling, which may be ore, barren pyrite, in fact any metallic minerals or quartz, and the record of the minerals present is found in the written notes. Blue coloring indicates evidence of faulting, either as the definite planes of movement or the crushed granite resulting from such movements. The sketches are always supplemented with copious notes as to the dip and strike, character of mineralization, and condition of the surrounding granite.

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Alundum Extraction-Thimble Used in the Determination of Copper

The photograph, Fig. 1, shows the apparatus a little less than half size, consisting of a filtering-flask fitted with rubber stopper through which passes a bent glass tube, and an extraction-thimble fitted with rubber stopper through which passes a glass tube of 0.25-inch bore. Both tubes are connected by a short piece of rubber tubing.

A section of a thimble is shown in the photograph; the tube extends to within 1/8 in. of the tapered end.

The object of using the thimble is to remove the acid from the beaker after all the copper has been precipitated. Time is saved, the copper is not exposed to the acid alone, and there are none of the losses attending ordinary filtration. I have accomplished these results by means of a piece of perforated platinum fastened in the end of a (1.25-in. bore glass tube and a filter-mat of asbestos, but after my supply of proper length fiber became exhausted I could not replenish it even after purchasing 14 lots from four different dealers.

The above apparatus may be used to remove at least seven-eighths of a supernatant liquid from a settled precipitate without disturbing the latter.

The application of the thimble is best shown by partly

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Wood Burning Assay Furnace

Wood burning assay furnaces are made with single and double muffles and are much like the soft coal furnaces except that a larger firebox and grate are used. Wood is usually sawed in 2-foot lengths and with dry wood the muffle may be easily heated sufficiently for assaying. Hard wood is much to be preferred as it does not bum out as rapidly, but almost any kind of dry wood may be used.

The large firebox and the grate, which is set about 8 inches below the bottom of the fire-door are the principal distinguishing characteristics of a wood-burning assay furnace.

Last fall, having a number of ore samples from mine-development work carried on in spite of the “Revolution,” I was forced to do my own assaying again, after a lapse of many years. This gave me an opportunity to build a furnace for crucible assaying, using wood for fuel, along lines which had been developing in my mind since the time 20 years ago, when as general factotum at a little mining camp in western Chihuahua, Mexico, I had converted a crucible charcoal furnace into one using the reverberatory principle.

Wood-burning furnaces have been described in technical literature, but I believe the

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How to Estimate the Tin Content: Assay Determination

The object that the writer has mainly in view in presenting this paper is to draw the attention of those connected with the technical side of the industry to the unsatisfactory and by no means up-to-date methods employed in estimating the tin contents of an ore. At the same time, what is regarded, from the writer’s personal experience, as a satisfactory and reliable method is explained in detail. It is a curious fact that for the last 25 years tin-assay methods have made little or no advance, while those now in general use in connection with copper and lead ores can scarcely be compared with those then obtaining, so greatly have they been improved upon. Though it is not altogether expected that the method herein advocated will at once meet with general approval, the writer hopes the resultant discussion may bring out points that have hitherto escaped detection.

Tin Fire Assaying Methods

The old Cornish method of smelting with anthracite is now obsolete. The cyanide assay, although unreliable, is still much used because of its simplicity. In the Malaya many buyers of tin ores use the cyanide assay, the smelting being carried out generally in a benzine furnace.

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Electrolytic Refining: Silver – Gold – Copper

The refinery takes the bullion purchased by the receiving department, and carrying more than 200 parts of precious metals in 1,000, or, in mint parlance, over 200 fine, and separates and refines the various metals contained therein, using electrolytic processes exclusively.

Bullion containing silver is treated in cells charged with a nitric electrolyte. These cells produce fine silver and leave a residue rich in gold.

The residue from the silver-cells, together with crude gold bullion, is treated in cells having a chloride electrolyte. These produce fine gold and leave a residue containing silver chloride. The latter is reduced to the metallic state with zinc and is then treated in the silver-cells.

The various waste solutions and the wash-waters, after being freed from the bulk of their precious metals, still contain copper and other metals. These are removed by scrap-iron, and are then treated in the copper-cells, having a sulphate electrolyte. These cells produce pure copper, and collect a residue containing lead, some gold and silver, and all the metals of the platinum group that were in the bullion. This residue is relatively small, and is melted into bars and stored until sufficient accumulates to warrant treating it for platinum, etc.

The refinery occupies

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Where are Fluorite Deposits Found

Where are Fluorite Deposits Found is shown at a glance on map (Fig. 1). On it, you will see the great scarcity of fluorite along the Pacific Coast; its sporadic occurrence in the interior as in Idaho, Utah, Nevada, and Arizona; and the comparative abundance of fluorite deposits along the eastern margin of the region, particularly in Colorado and New Mexico. This is not fortuitous; it expresses beyond doubt the concentration of fluorine in the province of alkaline rocks, extending through eastern British Columbia, Montana, South Dakota, Wyoming, Colorado, New Mexico, and Texas, continuing from there to old Mexico.

California.—Fluorite is rare in California. Minor occurrences are mentioned from small lead-zinc deposits near Azusa, and at Santa Catalina Island, both in Los Angeles County. There is a small occurrence mentioned by Hanks with copper ore near Mount Diablo. Fluorite occurs in the Cerro Gordo district, Inyo County, as veinlets in tremolitic marble. Syenite dikes are present. More is found in the Darwin district, same county, with lead and calcite veins in contact metamorphic rocks. Another locality is in Mono County in the Sweetwater Mountains, Ferris Canyon.

Where are Fluorite Deposits Found Where are Fluorite Deposits Found

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2nd Period of Differentiation & Ore Deposition: Intrusions / Effusions

Since early Paleozoic times the Cordilleran Coast has developed an uneasy hinge line while eastward the peaceful ocean spread over future geosynclines. Intermittent effusions of mostly basic flows gradually increased and reached a maximum in Triassic and Jurassic times, at one time even extending to Nevada, Idaho, and Oregon, and here developing more differentiation in acidic and even alkaline surface lavas. During the maximum activity in the Jurassic, volcanoes with surface and submarine flows dotted the coast from the foot of the present Sierra Nevada to the Alaskan shores. Ore deposition is not much in evidence though doubtless here and there emanations arising from the deep sources of the flows produced some unimportant mineralization.

At the close of the Jurassic, impulses from the Pacific began to effect compression and folding in the western geosyncline. The latest sediments, the Mariposa beds, were welded against the already disturbed Paleozoic formations and the whole developed into a closely folded mountain range with superimposed schistosity. Into this region were forced masses of slowly moving magmas that congealed without much differentiation. The great coast batholith came into being, and, when exposed later on by an erosion of enormous magnitude, appeared as an almost continuous

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