Blogs
Supercritical Water Treatment of Refractory Gold Ores
Table of ContentsExperimental ProceduresSupercritical Water ApparatusProceduresPyritic Gold ConcentratesMetal Oxides in the Supercritical Water PretreatmentConclusions Supercritical water alters the structure of common sulfide minerals by partially removing sulfur from the mineral structure. This discovery has been applied to the treatment of pyritic gold ores to improve precious metal recovery without generating or utilizing environmentally sensitive products such as SO2, chlorine, or
Water Jet Assisted Rock Cutting
Table of ContentsDiscussion of Jet-Assisted CuttingLaboratory & Field Experiences Tool Force Reductions-Importance of Jet PositionTool Force Reductions-Effect of Bit VelocityReduction of Dust Frictional Sparking and Machine VibrationReduction in Bit WearDisc Cutter Force ReductionsConclusions High-volume, low-pressure water jets have been employed for erosion of loosely consolidated rocks for centuries. This excavation method finds application in specialized circumstances even today. The use of
Cobalt Recycling
Table of ContentsGeneral Cobalt Recycling Process DescriptionCobalt Industry Flow ModelsCobalt SuperalloysCobalt Magnetic AlloysTool SteelsStainless Steels Heat-Resistant Steelsand Other Alloys (Excluding Alloy Steels and Superalloys)Miscellaneous and Unspecified UsesCatalystsOther ChemicalsCobalt Material FlowsSummary World resources of cobalt appear ample for the foreseeable future; however, political and economic events have caused concern over the availability and reliability of an uninterrupted supply. Because of this
Underground Leaching & Hydrology
Table of ContentsHydrologic Data AcquisitionExtrinsic PermeabilityHydrodilation of Fractures Underground in situ leaching is a method of in situ leaching which takes advantage of existing underground mine workings to gain preferential access to a deeply buried ore deposit. With this method of leaching, injection and recovery wells are collared in existing underground mine drifts and drilled into an undisturbed portion of
Effect Grinding Mill RPM Speed, Loading & Ball Size on Mineral Liberation
Grinding is generally considered to be a size reduction operation. However, in most cases the primary objective of grinding is the liberation of valuable minerals from gangue material, irrespective of the amount of size reduction required. If fracturing of an ore occurs in a random manner, it may be possible to use the grain size distribution of the valuable mineral
Bioleaching Refractory Gold Ore
Table of ContentsBioleacling ExperimentsMechanism of Gold — Bearing Pyrite Leaching Bacterial extraction of gold from sulfide bearing ores has been studied by many investigators. If gold occurs finely disseminated within the sulfide ore matrix such as in pyrite, arsenopyrite and pyrrhotite, the leachant can not penetrate into the inside of solid ore in order to leach the enclosed submicron size
Column Flotation Pilot Scale Testing
Table of ContentsPilot Plant DescriptionPilot Plant Operation Flotation feed was obtained at the various preparation plants by diverting slurry from either the thickener feed, classifying cyclone overflow or fine refuse sump depending on the plant circuit. In each case, the slurry was obtained from a waste stream prior to any flocculant addition and stored in a 650 liter (170 gallon)
Cryogenic Plant at Mining Metallurgical Processing Plants
In the 1940’s a top blown water-cooled oxygen lance was developed to inject oxygen into liquid iron. This process, the LD or BOF process technique, today is used in 65% of the world’s steel production, and represents the largest oxygen market for temperature enhancement in steel and non-ferrous smelting applications. There are three major approaches to the use of oxygen
Gallium Solvent Extraction
Recently, details of a study optimizing gallium and germanium extraction from zinc residues using H2SO4 leaches was published. In the process, filtrates containing gallium and germanium along with other impurities such as iron, copper, zinc, and cadmium are produced. The focus of this paper is the recovery of gallium from these solutions. It has been reported that in an H2SO4
Sodium Silicate in Phosphate Flotation
Some factors adversely affect the efficiency of anionic flotation of phosphate in the absence of sodium silicate, thereby decreasing the concentrate grade. Impurities originally present on the quartz surface might be responsible for this adverse effect, but the precipitates heterocoagulated onto the surface of quartz also appeared to play a role. Dissolved ions, especially Ca++, can be present in considerable
Making Titanium Pigments
Chemical Processes-Pigment Grade Titanium Dioxide by Hydrochloric Acid Leaching The following reactions give the chemistry of this process: CaTiO3 + 4HCl = TiOCl2 + CaCl2 + 2H2O The titanium is in solution as TiOCl2. It is then hydrolyzed to TiO2 as follows: TiOCl2 + H2O = TiO2 +2HCl The hydrolysis is brought about by dilution of the acid, heat and
Screening Concentrate to Remove Contaminants
This was a unique idea; to use a size separation device in a mineral separation. As metallurgists, we were taught in school to use any physical property difference available to make the mineral separation. The idea was a departure from conventional processing flowsheets employed by the majority of mineral processing plants. Plant testing began with a used, circular, oscillating, 1.2m
Grinding Coal Water Slurry
The pilot mill used was 44 cm i.d. and 60 cm i.l. with a volume of 91,250 cm and was fitted with six one-half inch lifter bars. The ball charge was made up of 2,200 one-inch balls for a bulk volume of 36,500 cm³ (40% loading and a void volume of approximately 13,700 cm³ (38%). All tests were run at
MBT 2 Mercaptobenzothiazole Flotation Collector
To study the effects of collector and hydrogen ion concentrations on the floatabllity of sulfide minerals, a series of flotation experiments were conducted in which flotation recoveries as a function of pH were measured by flotation tests in a laboratory flotator. The results of flotation tests using -100 +200 mesh size galena particles as a feed, MBT as a collector,
Iodine Gold Leaching
Over the last few years there has been an intense effort to identify lixiviants other than cyanide for gold and silver leaching. Bromide and iodide also exhibit the ability to form polyhalide complexes. This characteristic promotes the dissolution of Br2(s) and I(2)s in aqueous solution. Iodine reacts with iodide ion as follows: I(2)s = I2(aq)………………………………………………………..(1) I2(aq)+ I- = I3-…………………………………………………….(2) The triiodide
Improving Acid & Fluxed Pellet Metallurgical Properties
Table of ContentsProduction Pellet ComparisonMetallurgical Tests by SizeBench Scale Pelletizing TestsEffect of SilicaBentonite EliminationImproved Organic Binder PelletsIncreased Porosity PelletsFlux Addition RateMaking Fluxed PelletsInstallation of Roller Screens in Balling CircuitsChange of AdditivesCoal Burning Production pellets from each Minnesota taconite operation were obtained for baseline metallurgical testing. Concentrate from several of the operations was obtained for more intensive studies. Bench scale pellets
Determine Froth Flotation Kinetics
Table of ContentsFlotation Rate ApproachesFlotation Cell ModificationsKinetics of FlotationReview of Previous TheoriesDevelopment of Modified, First Order EquationLaboratory Experiments Froth flotation of minerals is one of the dominant concentration processes available today. By this process, finely divided mineral particles, within a pulp, separate according to the hydrophobicity of their chemically modified surfaces. Hydrophobic mineral particles are collected and transported from the
Surfactants & Mine Dust Control & Effect on Flotation
Dust measurements in mines clearly indicated that the major mineral dust exposure is due to loading and transport of the ore from the mining areas. One approach to the solution of this dust problem is the application of water sprays to reduce dust dispersion. Wetting of broken rock is very effective in preventing fine dust from becoming airborne by binding
L / D Ratio in Overflow Ball Mill Design & Operation
Ball mill shape factors in the period prior to 1927 averaged 1.1/1 for 29 center discharge mills and 1.0/1 for 30 peripheral discharge mills. With the resumption of new plant construction after the 1930’s depression, the Morenci concentrator continued the 1/1 ratio with its 3.1 x 3.1 m (10 x 10 ft) mills. The ratio was increased progressively from then
Column Flotation Cell Residence Time Distribution RTD
Table of ContentsRTD ModelModelling of the residence time distribution data We present the results obtained in a study of the residence time distributions of solids and liquids in two and three phase systems in a column flotation cell. The effects of various flotation parameters on these residence time distributions of the collection and cleaning zones are also reported. The data
Selling a Mining Property
Table of ContentsThe Decision to Sell the Mining PropertyPackaging the PropertyMarketing the PropertyInvestigation and Due DiligenceNegotiating a PriceAgreementClosingsPost ClosingSOLD Very few mineral properties spend their entire lifespans from discovery to depletion in the hands of one owner. More likely, properties will have several owners, and partial interests may change quite often. Similarly, mineral companies are bought and sold with frequency, in
Factors Affecting Ball Mill Grinding Efficiency
The following are factors that have been investigated and applied in conventional ball milling in order to maximize grinding efficiency: a) Mill Geometry and Speed – Bond (1954) observed grinding efficiency to be a function of ball mill diameter, and established empirical relationships for recommended media size and mill speed that take this factor into account. As well, mills with
Recommended Ball Mill Speed & Liner Configuration
With particular reference to mill size, it is apparent that a change in diameter in a large mill is relatively far less significant than the same change in diameter for a small one. For example, using well established relationships between power draw and mill diameter and speed, 50 mm (2 inches) of liner wear results in about 14 percent power
Silver Refining
Precipitates mixed with diatomaceous earth from the precipitation filter unit are dried in a filter press and mixed with borax and soda ash. This mixture is then melted in a diesel-fired furnace and cast in a silver dore cone. This cone is then melted in another furnace into an anode 7 inches by 9 inches by ½ inch thick for electrolytic