Blogs
Horizontal Cycloning
The invention is based on the discovery that the reason why big hydrocyclones which are positioned vertical need a comparatively high feed pressure is that, owing to their great length, these hydrocyclones contain such a tall liquid column that gravity becomes an important factor and influences the operation of the hydrocyclone. If however, the hydrocyclone is given a sufficient tilt
Compare High Frequency Screens & Hydrocyclones
Table of ContentsPilot Plant StudyDesign of a Full Scale CircuitResults Hydrocyclones are currently the most commonly used classifiers in wet closed circuit grinding systems. Some recent papers, however, give evidence that high frequency vibrating screens can be a viable alternative to hydrocyclones for a wide variety of grinding applications. In principle, classifier selection for closed circuit grinding should be based
High Efficiency Separator
The industrial grinding process has undergone changes to better address the market and economic needs. Fine grinding of dry materials has developed to the point where classifying linings and fine ball charges improve mill efficiencies. Roller mills as well have wide acceptance due to their power efficiencies. The mill, by its nature, cannot provide the specific particle size or range
Staged Classification & Grinding Circuits
Table of ContentsSpecific Size and Density Separation ProcessesPrincipal Grinding Circuit Designs Application Examples Minerals beneficiation commonly requires initial crushing and grinding so that the mineral phase we seek to concentrate is adequately liberated to obtain a product of specified grade at optimum recovery. To some degree this also is true for coal preparation. In the comminution process we liberate not only
Grinding Circuit Audit
Table of ContentsCrushing CircuitGrinding MillsInstrumentation And Process Control The Island Copper concentrator was designed to process 30,000 t/d of copper ore containing 0.52% Cu and 0.017% Mo with payable gold, silver, and rhenium values. Separate copper and molybdenum flotation concentrates are produced and currently sold to customers in Asia, Europe and the North America. The comminution circuit as originally installed
Particle Size and Selectivity of Sulfide Flotation
Table of ContentsExperimental ProcedureResults and Discussion A very important factor in froth flotation is the use of surface-active chemicals to form a froth in which minerals or coals are retained, thus allowing for valuable component enrichment. Despite the importance of frothers, surprisingly little systematic scientific work has been performed with the goal of quantifying frother mechanisms and the influence of
Air-Sparged Hydrocyclone for Fine Gold Flotation
Pilot-scale tests indicate that effective concentration of fine gold from Colorado River sands can be achieved by flotation with the air-sparged hydrocyclone. The fine sands (55% minus 400 mesh and 0.01 opt) from gravity concentration were processed with a 5-cm air-sparged hydrocyclone (capacity -1.0 tph dry solids). Concentrate grades as high as 5.0 opt were produced in a single stage
How to Extract Precious Metals from Geological Brines
It is now well documented that trace amounts of silver, gold, and platinum group metals occur in certain geothermal brine deposits. A significant body of literature has been generated over the last twenty years which describes attempts to quantify the frequency and levels of these precious metals in the brines. There are numerous reports of the presence of precious metals
Effect of Mill Load Level and Speed on SAG Mill Operation
Table of ContentsCircuit DescriptionSag Mill Process Control ChallengesEffects of Major Process Variables on SAG Performance The SAG milling of ores with markedly variable grinding rates presents definite process control challenges. Decisions must be made regarding the selection of the most appropriate combination of mill volumetric load level, percent solids, and mill speed for the combination of ore types being processed
Dewatering Aid
The moisture content of coal has become more important in the product analysis. The high content surface area and corresponding high moisture of fine coal can contribute to most of the overall product moisture. As the preparation engineer exhausts his talents and capital budget to bring product moisture into compliance, alternate methods of fine coal dewatering must be considered. One
Merrill-Crowe Plant Design Factors
The removal of metal values from cyanide solutions, fortunately, can be done in several ways. The oldest practiced method is, cementation with zinc, or Merrill-Crowe. The original patent for recovery of gold and silver from cyanide solutions described precipitation with zinc dust. Most early practitioners, however, used granules of zinc in a successful attempt to avoid payment of patent royalties.
Hydrodynamic Bearings for Large Diameter Machines
The hydrodynamic bearing has the following characteristics: Lubricant film thickness and pressure are maintained by lubricant which is drawn into a wedge shaped zone between the journal and the bearing, due to their relative velocity and the viscosity of the lubricant. Lubricant flow conditions are laminar. Lubricant film thickness is sufficient to prevent metal to metal contact under all operating
Deister Flotaire Column Flotation Cell
The FLOTAIRE Flotation Cell is a column flotation cell designed to utilize aspirated gas in surface tension lowered water to generate extremely fine bubbles. The non-mechanical distribution of the fine bubbles throughout the column without agitation or turbulence allows for greater bubble/particle adhesion. The combined effect of these operating conditions shows enhanced flotation recovery of both very fine and very
Copper Electrowinning
The very survival of the U.S. copper industry is presently tied to the leach SX-EW process, a technology which 15-20 years ago was considered too radical and far fetched to be accepted by the industry. It came to life rather dramatically with the Ranchers Bluebird Mine and shortly thereafter with the Cyprus Bagdad plant. All of a sudden, it was
Classification & Concentration of Heavy Minerals
Table of ContentsPerformance of a Production CircuitTheoretical Framework The recovery of heavy minerals by gravity concentration during grinding is practiced widely in the minerals industry. Studies have shown that the grade and recovery of the concentrate depends not only on the performance of the concentrator but also on the degree of liberation achieved in the mills and the scavenging action
Charge Motion inside a SAG Mill
For proper design of SAG mills and other types of grinding mills, the operating conditions have to be defined. Predicting the composition of the SAG mill charge is a difficult task since a number of significant phenomena associated with the charge motion must be taken into consideration. These observations and assumptions led to the recognition of the need for better
Autogenous Grinding Iron Ore
Hibbing Taconite is located near the center of the Mesabi Range in Northern Minnesota 100 miles from the Canadian border and 80 miles north of the Lake Superior Port Cities of Duluth and Superior. Current owners of Hibbing Taconite are Bethlehem Steel Corporation, LTV Steel, Pickands Mather and Stelco. Inc. Pickands Mather, a subsidiary of Moore McCormack Resources, Inc., Stamford,
Air Classification Working Principles
Regardless of the mechanical design features of a particular air classifier certain basic principles apply. Specifically, there are two forces at work: An air drag force An inertial or centrifugal force. The air drag force has an increasing influence as particles become smaller. A very small low mass particle is easily carried along with an air stream even when turning
Bioleaching Test Procedure
Pulps of 20% solids is prepared from -200 mesh pyrite concentrate (after froth flotation), and is inoculated with 5% (V/V) of adapted bacterial solution. The bioleaching tests is carried out in 250 ml Erlenmayer flasks, each contained about 220 ml pulp. The pulps is aerated with air bubbling at one liter per minute air flow rate, and is continuously agitated
Heap Leaching in Cold Weather & Winter
Extended freezing conditions exist in many parts of the world in the winter because of latitude or high altitude or both. Such conditions, coupled with the sprinkling techniques commonly used in heap leaching, result in formation of layers of ice which inhibit leaching by tying up solution inventory on heap surfaces and shutting off solution percolation. Loss of leaching availability
Heap Leach Feed Preparation
Some gold and silver ores are difficult to successfully heap leach because of the high percentage of clay, and/or fines which are intrinsic in the material or generated by the crushing or ore preparation. This type of ore can result in extremely slow percolation during heap leaching. Channeling can result which promotes dry areas within the heap, leach solutions may
Heap Leaching at Altitude
It is feasible to conduct cyanide heap leaching at high altitudes as has been demonstrated by a number of pilot and commercial operations in the altiplano of the Andes Mountains. Operations at elevations in excess of 3000 meters (9800 ft) must be conducted with care to insure that heaps are fully permeable and the lixiviant solution does not become depleted
Heap Leaching with Sea Water
There are locations on the west coast of South America, in Australia, and in the California internal desert where fresh water is practically unavailable. It has been found that precious metal dissolution can be accomplished in sea water or in strong brine provided the leaching environment is adjusted to compensate for the buffering characteristics of the brine solvent and equipment
Bioleaching Carbonaceous Gold Ores
Table of ContentsFacultative Thermophile Bioleaching of Carbonaceous Gold OreMicrobial Inhibition of Preg RobbingBioleaching, CIL, and Blanking Agent The previous tests demonstrated the use of facultative and extreme thermophiles for refractory sulfide gold ores and flotation concentrates. The following tests were conducted on carbonaceous gold ores to evaluate response to bioleaching. Facultative Thermophile Bioleaching of Carbonaceous Gold Ore The facultative thermophile