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By Arthur W. Griffith

Ozark Lead Company, a wholly owned subsidiary of Kennecott Copper Corporation, was formed in 1961 to operate in the State of Missouri. The orebody presently being mined was discovered in January of 1962, and over a quarter of a million feet of drilling was done to determine its value and extent. In addition, a development shaft, six feet in finished diameter, was drilled into the orebody by an oil field rig in order to support the results of the core drill samples and to obtain bulk samples of ore for metallurgical pilot plant testing, upon the results of which the primary flowsheet was established. The design criteria developed from the flowsheet was based upon a 6000 TPD plant throughput and the subsequent engineering and construction of the mine and concentrating plant was completed in June 1968. The plant, which is designed to mine and mill 6000 tons of ore per day and produce 60,000 tons of lead and 8000 tons of zinc in concentrate annually, is located approximately 110 air miles south- west of Saint Louis. MINERALOGY The orebody occurs in the Bonneterre dolomitic limestone formation in the form of irregular masses of disseminated sulphides in essentially horizontal beds. The Lamotte sandstone underlies the Bonneterre formation and is barren in values. Principal ore minerals include galena with lesser amounts of sphalerite and some copper minerals. Galena is found to be massive

Jan 1, 1970

By Glenn Allen

SAN FRANCISCO Mines of Mexico, Ltd. owns and operates an extensive group of claims in the San Francisco del Oro-Santa Barbara district, about 15 miles southwest of Parral, Chihuahua. The property comprises the mines, aerial tramways, flotation mill, power plant, shops, offices, assay and testing laboratories, modern hospital, water and sanitary system, quarters for miners, mechanics and operators, a well housed colony for Mexican staff employees and residences for foreigners. Each colony has a club house and mess and tennis courts. The employees have constructed a nine-hole golf course. In other words, the property is self-contained and completely integrated for production of lead and zinc concentrates from complex sulfide ores.

Jan 1, 1930

By Jay J. Burns

TWO zinc concentrating mills are operated by the St. Joseph Lead Co. in St. Lawrence County, N. Y. The Edwards mill is operating at present only sixteen hours a day treating 400 tons daily. The metallurgy at Edwards presents no unusual problems therefore this discussion is mainly limited to the metallurgy of the Balmat ore. The Balmat mill has a capacity of 1,250 tons per day and the operating crew consists of three shift bosses each with five millmen per shift. Two crusher operators work on each of two shifts and one cleanup man on day shift. The repair crew is made up of a foreman and three repairmen, one of the repairmen being capable of taking over any operating job in the mill from shift boss down. Each millman is capable of handling the next job in line and several men in the yard crew are broken into handling the start-off job in the mill so that temporary shortages of men do not cause extensive overtime. Sphalerite, pyrite, and galena, the principal ore minerals, occur in a gangue of calcite, dolomite, and silicates, especially diopside, plus tremo-

Jan 1, 1947

By H. K. Martin

IN September 1954 the Lavender pit concentrator at Lowell, Ariz., began treating low grade porphyry copper ore from the nearby Lavender mine. Nominal capacity of the mill is 12,000 tpd, but production now averages 16,226 tpd. Plant design was somewhat affected by the re-use of old equipment and the substantial re-use of old buildings. A breaking-in period between June 24 and Sept. 1, 1954, was devoted to training operators and making minor changes in launders, chutes, and piping. From Sept. 1, 1954, to July 1, 1956, the mill treated 8,598,105 dry tons of ore, from which 556,541 tons of concentrate were produced, containing an indicated 144,055,185 lb of copper.

Jan 11, 1957

By H. R. Stahl

FIVE mills are operated in Southeast Missouri by the St. Joseph Lead Co.; these have a total rated capacity of 24,300 tons per day divided as follows: Federal, 12,000 tons; Leadwood, 4800 tons; Desloge, 3600 tons; Bonne Terre, 2400 tons; and Mine La Motte, 1500 tons. These concentrators are similar in a general way, differing mainly in size and type of equipment and in minor variations in flow sheet. No attempt is made rigidly to standardize procedure in the various mills in spite of a general similarity in the ores. Each mill may be regarded as a separate laboratory in which new ideas and changes may be tried. A generalized description of the process is given, noting important differences in procedure at the various plants. The concentration process may be divided into five main stages: dry crushing, wet grinding, desliming and classification, tabling, and flotation.

Jan 1, 1947

By Robert Ammon

THE milling practice at Mascot, at present, consists of dry crushing to 5/8 in., jigging, fine grinding, and flotation. The ore arrives at the mill from two mines, No. 1 mine shaft being located in the mill proper, and No. 2 mine shaft being situated about 2000 ft. east of the mill. No. 2 mine is served by a coarse-crushing plant and aerial tramway to the mill bins. In jigging the No. 2 mine ore, 50 per cent. of the mill feed is rejected by the jigs as a jig tailing ranging from 5/8 in. to 10 mesh; the balance of this ore, after removing a jig concentrate, is ground to flotation feed. In jigging No. 1 mine ore, approximately 80 per. cent. of the mill feed is rejected as a coarse jig tailing, and the balance is ground to flotation feed without the removal of a jig concentrate. The difference in the treatment is due to the fact that No. 2 mine ore carries a higher content of zinc than that from No. 1 mine. Of the total concentrates produced, 30 per cent. are made on jigs and 70 per cent. by flotation. At present, 1350 tons of No. 2 ore and 800 tons of No. 1 ore are treated each 24 hours. The recoveries for a typical week are as follows: Heads 3.55 Jig concentrates 61.30 Jig tails 0.80 Flotation concentrates 60.60 Flotation tails 0.09 Extraction 86.50 The associated minerals are a straw-colored sphalerite, dolomite, calcite, pyrite, quartz, and a small amount of greenockite, which occurs as a stain and sometimes small crystals along with sphalerite, but is comparatively rare. Pyrite is present in small quantities, usually less than 0.5 per cent.; quartz occurs in bands a few inches thick. A complete analysis of the ore is as follows:

Jan 9, 1924

By H. R. Stahl

THE disseminated lead district of Southeast Missouri lies 70 miles south of St. Louis. The only metal of economic importance in the ore is lead, but minor amounts occur of iron, zinc, copper, cobalt, nickel, silver and cadmium. These minor metals, as might be expected, tend to concentrate in both the flotation and table middlings. In the past, some zinc has been recovered by differential flotation. The silver and cadmium tend to associate with the zinc, and some recovery is made of these two metals at the smelter. The lead occurs as galena, or lead sulphide. The minor metals are also present as sulphides. The presence of oxidized lead is suspected, but has not been definitely proved. The gangue is chiefly dolomitic limestone, with small amounts of sandstone and shaly glauconitic and chloritic minerals. The ore contains about 3.25 per cent lead, occurring as galena disseminated through the gangue. Some of the galena is very finely disseminated, and the mineral in the gravity tailings, or chat, is seldom or never in the free state. The method of treatment of the ore has been evolved over a period of 75 years; hence probably is not far from correct. The milling processes have tended toward simplification during the past 15 years, but recoveries have never been sacrificed for the sake of simplicity. In many cases, simplification of flowsheets has led to better recoveries and operating economies. A simplified flowsheet is shown in Fig. I. The St. Joseph Lead Co. operates four mills in the Flat River district, with a normal total capacity of about 21,000 tons per day, divided as follows: Federal mill, 11,000 tons; Leadwood mill, 4500 tons; Desloge mill, 3400 tons and Bonne Terre mill 2400 tons. The methods of concentration used at these plants are similar in principle; they differ mainly in details and in the type and size of the equipment used. The process of concentration may be divided into five main steps; i.e., dry crushing, wet grinding, classification with its attendant desliming, tabling and flotation. A brief description of these processes will be given, noting important differences in the various plants, and also noting the more important changes or developments of the past few years. DRY CRUSHING The run-of-mine ore is hoisted in skips, the capacity of these skips ranging from 2 ¾ tons to 8 ¼ tons. At the Desloge plant, the ore is hoisted in 2-ton mine cars on self-dumping cages. All ore is hoisted at shafts adjacent to the various crushing plants, no ore being transported on the surface. Primary breaking at all the mills is accomplished with 9E Telsmith breakers. Preliminary screening is provided ahead of most of these crushers, either by station-

Jan 1, 1943

Discussion of the paper of L. A. DELANO, presented at the St. Louis meeting, October, 1917, and printed in Bulletin No. 129, September, 1917, pp. 1267 to 1286. L. A. DELANO.-Since this paper was written, our daily mill tonnage has increased, from 2100 tons to 2700 tons a clay. We now use 11,000 lb. of chrome-steel balls of 2 ½ -in. maximum diameter, for an average crushing capacity of 275 tons per 24 hr., this giving a much higher crushing efficiency. I wish to call attention to two typographical errors in my paper as published. On page 1271, Table 1, the screen analysis of ore at the Bonne Terre mill should be stated in inches instead of mesh. - On page 1272, "the rolls average 185 tons per 24 hr., and have shown by test that 250 tons per hour can be maintained" should, of course, read "250 tons per 24 hours." THE CHAIRMAN (0. M. BILHARZ, Miami, Okla.).-Is the increased mill capacity due to improvement in the re-crushing of middlings or to keeping middlings out of circulation and treating them separately? L. A. DELANO.-AS was shown in Mr. Rabling's paper (Bulletin No. 128, p. 1161) the tonnage was raised by about 400 tons by simply changing the arrangement of screen openings in the jig bed and using punched plate instead of woven-wire screen. Then, by adding a ball-mill, we are taking from the jigs a much larger tonnage of middlings than before or as much as the ball-mill will crush. By sending the ball-mill product to tables and flotation, the jig capacity for original ore is increased. CHAIRMAN BILHARZ.-In your opinion, the satisfactory operation of a Hancock jig on a given ore requires adjustment of the length of the different screens and careful selection of screen openings? L. A. DELANO.-I think it does. In order to decide what screen openings to use on the jigs, we did a great deal of experimental work, making screen analyses of the various hutch products, and then hand-sorting the galena, middlings and chat from each size screen to determine the percentage of galena in each. Then adjusting our jig screens, we gradually worked the process up to a very efficient basis. ERNEST GAYFORD, Salt Lake City, Utah.-I would like too ask Mr. Delano whether the work of the Allen cone has been quite as satisfactory as the manufacturers claim for it.

Jan 1, 1918

By W. H. A. Timm

Lake Dufault Mines, Limited, is located ten miles north of Noranda, Quebec, Canada. Following discovery of a copper-zinc orebody late in 1961, metallurgical investigations of diamond drill core were conducted by Lakefield Research Limited during 1962 and 1963. These were followed by pilot-plant tests in May and June of 1964, utilizing underground development ore. Milling operations commenced on August 16, 1964, and reached rated capacity of 1300 tpd by October 1, 1964. Since that time, tonnage was gradually increased to a maximum of 1400 tpd and since January 1, 1968, gradually decreased to the present rate of 1100 tpd due to an increase in the hardness of the ore. The ore milled from start-up until January 1968, was mainly massive sulfides, consisting of a complex mixture of iron, Copper, zinc, and minor amounts of lead sulfides with important associated values in gold, silver and cadmium (average specific gravity of 3-8). From January 1968 until the present, the ore being processed is described geologically as a boxwork of sulfide stringers of chalcopyrite, pyrite, and pyrrhotite with some local dissemination in siliceous rhyolite (average specific gravity 2.9) supplemented by the massive copper-zinc ore. The limited size of the orebody and the mining method employed (open stoping by blasthole and slash benching methods) would have

Jan 1, 1970

By B. H. Cody

THE Morenci concentrator of the Phelps Dodge Corporation is a part of the project that was completed after five years had been spent in development of the open-pit mine, equipment and process testing in the former No. 6 concentrator, and construction of the reduction works. The reduction works, of which the concentrator is a part, is about a mile and a quarter southeast of Morenci, on the highway that leads up Morenci Canyon. The concentrator has a nominal capacity for the treatment of 45,000 tons of ore daily. The original plant, which has a rated capacity of 25,000 tons of ore daily and is now in its fifth year of operation, began production on Jan. 30, 1942. The addition, to increase the capacity 8o pct, began operation on Dec. 1, 1943. The equipment of the original plant has been described in MINING AND METALLURGY (May 1942). No changes in equipment were recommended for installation in the concentrator extension and only one major change, forced by a shortage of maintenance labor, has since been made. Metallurgical treatment has been altered in some ways as experiments progressed and as labor and economic conditions dictated. No complete description of the operation of the concentrator has been published, so this paper will record such operating and equipment changes as have been necessary, the operating methods that have been developed and the metallurgical results that have been obtained. Descriptions are given in the order of the processes with a flowsheet and an equipment list of each process for convenient reference. The questions asked by engineer visitors have guided the detail in which operation and maintenance are described. During the period Jan. 30, 1942 to Sept. 1, 1946, ore milled has totaled 43,595,253 dry tons, from which 1,643,885 tons of concentrate have been made, containing an indicated production of 783,164,809 lb of copper. The principal results obtained in operation of the concentrator during the years 1942 to 1945, inclusive, and to Sept. 1, 1946 are shown in Table 1. A graphic general flowsheet of the plant is given in Fig I. ORE The Morenci ore that is now being treated is a medium-hard monzonite porphyry in which the principal sulphide minerals are chalcocite and pyrite. A minor amount of covellite is present. Chalcopyrite and bornite have been observed under the microscope. The chalcocite occurs mainly as a coating on pyrite. Some of the coatings are so thick that the pyrite presents the appearance of being an inclusion in chalcocite. Some are less than one micron thick and are barely visible at 500 diameters magnification of a polished cross section. Some chalcocite is present as a dissemination in the gangue. Various oxidized copper minerals are present as a result of oxidation in place but they represent a minor proportion of the copper minerals of the ore body. Oxidation

Jan 1, 1947

By D. L., Hayes

THE concentration of zinc ore in Wisconsin is a comparatively simple process, although it presents problems that must be overcome in an efficient manner in such a way that installation and operating costs are low. As the ore deposits are small, the first cost of the concentrating plant must be low; while the low margin of profit makes it necessary to have the minimum operating costs. The original mills were copied from those of the Joplin district, as most of them were built and operated by Joplin millmen. These served the purpose well; they made a clean concentrate, which was the chief requirement at that time, as most 'of the mines were' considerably 'richer than the average at the present time, and wages and supplies were also considerably lower. ' The apparatus used at present has changed very little in principle. . The grizzly opening has gradually been increased to 12 in. and sometimes no grizzly 'is used. The crusher, gradually grew in size, the largest crusher has -an opening of about 24 by 13 in. and a 7/8-in. throw on the. eccentric shaft.

Jan 1, 1921

By Norman Weiss

There was a time in the early history of man's use of metals when ore could be directly reduced to usable form by the use of fire. In those days the term "milling," or its many synonyms signifying the concentration of an ore's metallic con- tents before smelting, was little known. Centuries later, even before Agricola, or even before the Greek and Roman civilizations, simple means were found to concentrate metallic minerals that possessed special characteristics such as high specific gravity, hardness, magnetic response, or simple appearance. In this way, the art of milling became valuable to civilization because it eliminated most of the cost and labor of transporting and melting the worthless nonmetallic part of an ore. As civilization became more dependent upon metals and solid fuels, the art of ore dressing (one of our synonyms) increased in importance and complexity, until today it has become a gigantic industry firmly based upon a mature but rapidly advancing technology. Technically trained people are needed in growing numbers to serve this industry.

Jan 1, 1970

By AIME

TO say that Milton Fies has been active in promoting the Southern Research Institute is a masterpiece of understatement. He is a director and trustee who was in on the ground floor when plans were first made for the Institute and since it became an actuality early in 1945 his interest and efforts continue. He talked about it at the last regional meeting of the Birmingham Section of the A.F.A. and has talked all over the South-and when he makes a speech he has really prepared it. He does not try to rival a political spellbinder, but his careful, concise English is always well thought out and to the point. Southern Research might be called his present hobby as it has been for the past two or three years. Another major interest has been his encouragement and training of engineering students. Active in the formation of the Student Chapter of the A.I.M.E. at the University of Alabama, for several years he saw to it that the students had a prominent engineer at each monthly meeting, usually taking them down to Tuscaloosa from Birmingham in his own automobile. He has also been keenly interested in the mining engineering activities at Tuscaloosa, both in the Bureau of Mines and the University.

Jan 1, 1946

The One Hundred Eighteenth Meeting of the. Institute was held at the Milwaukee Auditorium, on Tuesday,. Oct. 8, to Thursday, Oct. 10, inclusive, 1918, under the joint auspices of the Committee on Iron and Steel (Chairman, Prof. J. W. Richards), and the Institute of Metals Division (Chairman, William M. Corse), and simultaneously with sessions of the American Foundrymen's Association and of the. American Malleable Castings Association. It was preeminently a war meeting. It was attended by 104 members of the Institute. The social features, so far as the members of this Institute were concerned, were slight, but generous and appropriate entertainment was offered to the ladies, consisting of automobile sight-seeing trips, reception, concert and dance on Tuesday evening, a theatre party Wednesday evening, and -a banquet in-the Auditorium Thursday evening, at which the speakers were Charles M. Schwab, Director General of the United States Shipping Board Emergency Fleet Corporation, Major A. Radclyffe Dugmore, and W. H. Blood, Jr., Assistant to the President of the American International Shipbuilding Corporation. A joint session was held on Tuesday morning, at which an address of welcome was delivered by Hon. Emanuel L. Phillipp, Governor of Wisconsin, with a response by Benjamin D. Fuller, President of the American Foundrymen's Association, and the following addresses: Activities of the Army Ordnance Department, Especially as Applied to Foundry Matters. By C. S. Koch, Cannon Section, Production Division, Ordnance Department. Washington. D. C.

Jan 11, 1918

Jan 1, 1919

Jan 1, 1925

The 118th, meeting of the Institute, which has been arranged primarily for the benefit of the Institute of Metals Division and of those members who are particularly interested in iron and steel, will be held in the Milwaukee Auditorium, Milwaukee, Wis., on Oct. 8 to 11, 1918. This date has been selected because at that time, and at the same place, the American Foundrymen's Association and the American Malleable Castings Association will hold meetings. A notable exhibit of metallurgical and mechanical processes and products, at which over 165 firms will be represented, has been arranged in Machinery Hall, of the Auditorium Building. Wherever practicable, the machinery will be in operation. The program of the Institute's sessions was published in Bulletin 141. A special announcement of the meeting, together with a program of the sessions of the American Foundrymen's Association, has been mailed to every member who was thought to be directly interested in the meeting. A report of the meeting-and of the discussion of papers will be printed in the December Bulletin.

Jan 10, 1918

A special meeting of the Institute, at which the Institute of Metals Division will join with those members who are most interested in iron and steel, and in coal and coke, will be held in Milwaukee, Wis., October 8 to 11, 1918. The technical program is as follows: INSTITUTE OF METALS DIVISION Tuesday morning, October 8: The Metallography of Tungsten, by My Jeffries. (Bulletin No. 138, p. 1037.) The Constitution of the Tin Bronzes, by S. L. Hoyt. Paper, title not given, by C. H. Mathewson. Notes on Babbitt and Babbitted Bearings, by Jesse L. Jones. (Bulletin. No. 140, p. 1397.) Oxygen and Sulphur in the Melting of Copper Cathodes, by S. Skowronski. (Bulletin No. 135, p. 645.) The Relation of Sulphur to the Overpoling of Copper, by S. Skowronski. (Bulletin No. 135, p. 651); with discussion by Philip L. Gill. (Bulletin. No. 140, p. 1156.)

Jan 9, 1918

A joint meeting of the American Institute of Metals Division, and the iron and steel members of the American Institute of Mining Engineers; with the American Foundrymen 's Association, has been arranged for Milwaukee, beginning on Tuesday, October 8, 1918. The papers to

Jan 8, 1918

By N. B. Pilling

The deleterious effect on the mechanical properties of copper, re-sulting from heating in contact with reducing gases, is well known, but the mechanism of the action does not appear to have been definitely established. The purpose of the present investigation was not to determine the exact variations in physical quality of commercial copper, with its various impurities, as dependent upon the composition of the gas, temperature of exposure, etc., but rather to study the nature of the action and the conditions under which it occurs. The physical result of the so-called "gassing" of copper has been generally described as the development of "brittleness." There appears to be a striking decrease in tensile strength, associated with a considerable loss of ductility, and a small copper strip or wire affected in this way can be snapped in two when bent. Larger articles may have an outer layer alone affected, which can be detached from the core by hammering or bending. Perhaps the earliest reference to this subject is that of Heynl in 1900, and among the later observers may be mentioned Archbutt,2 Bengough and Hill,3 Johnson,4 Mathewson and Thalheimer,5 and Ruder.6 Bengough and Hill, while working with arsenical copper, were the first to suggest the possibility of the formation of gases within the copper itself, while Ruder endeavored to explain the action by the reduction of the

Jan 1, 1919