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By H. R. Peterson

The control of autogenous grinding circuits is very similar to the control of conventional grinding circuits. In both circuits the classifier must be operated to achieve the required degree of mineral liberation. Crude ore grade and grinding mill density are important in both circuits. The biggest difference between the control of the two circuits is the pronounced effect that crude ore changes have on autogenous circuits. The importance of crude grade, weight recovery, size and hardness is greatly magnified because the crude ore in the autogenous circuit is also supplying the grinding media. Crude ore sizing is a particularly critical factor in achieving efficient primary autogenous milling. Because of the above, computer control is advantageous for autogenous circuits. Changes in crude ore may necessitate rapid changes in the entire circuit control strategy, and only a computer can facilitate these changes. Also, the techniques of control are very different for conventional and for autogenous grinding. Set-point control is usually satisfactory in conventional circuits, but the multiplicity of varying conditions in an autogenous circuit usually require some type of computer optimizing search routine. Autogenous mills can be separated into two general types. In primary autogenous mills the media is obtained from the mill feed, and in pebble mills the sized pebble media is added separately from the material being ground. PRIMARY AUTOGENOUS MILL CIRCUIT CONTROL - FIGURE 1 Power Draw Primary autogenous mills are usually run at full motor loading so production will be at maximum. Therefore, power draw must be closely controlled; this is done by adjusting feed rate. The versatility of computer control is extremely valuable for power control, especially during starting and stopping. To bring the mill power up as fast as possible at

Jan 1, 1982

Jan 1, 1909

Jan 1, 1932

Jan 1, 1934

By AIME AIME

WHEN Vice-chairman Calvert Townley calls the next meeting of the Executive Board of the American Engineering Council of the Federated American Engineering Societies to order in Washington on Sept. 30, it will be the first meeting in that city for almost a year. It is probable that the Board will decide at this meeting whether future board meetings will be held regularly at the headquarters in Washington or whether the plan of meeting at various engineering centers throughout the country, as has been done during the past year, will be followed. The most important business coming before this .meeting will be the election of a president to succeed Herbert Hoover, who resigned after he became Secre¬tary of Commerce. Nominations to fill this vacancy were ordered 'at the last meeting of the Executive Board, to be reported at the September meeting. Special attention will be given the plans for the engineering assembly, extension of employment service, question of licensing and registration of engineers. The engineering assembly, committee has been appointed, with A. P. Davis as chairman, the other members being Philip N. Moore, L. P. Alford, John C. Hoyt and F. A. Vaughn. This committee will work out detailed plans for an assembly to be held in con¬junction with the annual meeting of the American Engineering Council in, January. Tentative plans provide for a three-day session; one day to be given to special meetings of the executive boards of member organizations and committees of the American Engineering Council; one day to the sessions of the American Engineering Council; and at least one day to discussion of some, special topic.

Jan 1, 1921

Edgar Hall, Tenterfield, New South Wales (communication to the Secretary): Mr. Klepetko* asks for information showing at what percentage antimony and arsenic, as impurities, begin to affect injuriously the quality of brass.

Jan 1, 1899

Jan 1, 1942

Jan 1, 1930

New Products Equipment

Jan 8, 1951

Jan 1, 1969

In preparation for the 119th meeting, New York, Feb. 17 to 20, 1919, the following committees have been appointed: Committee on Arrangements ALLEN H. ROGERS Chairman. NY. S. DICKSON, Secretary. J. E. JOHNSON, JR. F. T. RUBIDGE. P. G. SPILSBURY. H. C. PARMELEE. FOREST RUTHERFORD. Committee on Annual Dinner Committee on Luncheon F. T. RUBIDGE. FOREST RUTHERFORD, Chairman. E. B. STURGIS. E. MALTBY SHIPP Committee on Patriotic Meeting H. C. PARMELEE, Chairman.

Jan 11, 1918

Jan 1, 1892

By W. S. Morris

THE East Texas oil field is the largest in the United States and perhaps the largest 'in the world ; likewise, it is one of the most interesting. The East Texas oil field is a water-drive field. Small amounts of salt water were produced from wells on the western side of the field from the bt-ginning of the development. By the end of 1933 (the field having been discovered in September 1930) water production had reached 9000 barrels per day. By the end of 1936, approximately 2000 wells were producing about 45,000 barrels of water per day, and the problem of salt water disposal attracted the serious attention of the operators. Salt water production in the field has steadily increased and today approximately 450,000 barrels of water per day is produced while the oil production averages about 375,000 barrels. The disposal of this salt water has therefore become one of the major operating problems. Various methods of salt water disposal have been tried in the East Texas field. Evaporation in open pits proved

Jan 1, 1944

Jan 1, 1941

Jan 1, 1940

Jan 1, 1943

Jan 1, 1943

Established as a Division March 24, 1922 R B Gilmore, '57, Chairman G L Yates, '56, Vice-Chairman Phil J Lehnhard, '56, Vice-Chairman John R McMillan, Past Chairman T A Pollard, Treasurer Joe B Alford, Executive Secretary 800 Fidelity Union Building Dallas 1, Texas

Jan 1, 1955

Truman H. Aldrich '78 W. S. Ayres '73 Andrew A. Blair '75 Walter M. Brodie '72 H. M. Chance '74 Fred'k G. Corning '77 Ralph Crooker '81 A. W. Crookston '80 George M. Davidson '81 W. B. Devereaux '80 H. S. Drinker Founder

Jan 1, 1929

Jan 1, 1942