Mineral Processing Engineering

Deposition and Oxidation Mercury Ores

This study was initiated to investigate the occurrence of cinnabar in the oxidation zones of some mercury sulfide deposits. Seven mines or mine districts were visited and samples were taken from both the oxidation and primary zones of these deposits in order to compare their mineralogies and assess the chemical changes that took place during oxidation. As a result of the study of these specimens, several limiting factors are suggested for the chemical environments and processes active in both the deposition and oxidation of mercury sulfide deposits.

Mt. Jackson Mines Guerneviile, California

The Mt. Jackson mine is a cinnabar deposit at the intersection of several faults with a serpentinite “sill” in Franciscan sandstones and shales. Footwall silica-carbonate rock consists of magnesite, quartz, and chalcedony, with accessory chromite, kaolinite, pyrite and millerite, and is cut by magnesite, dolomite, and quartz veins. Cinnabar occurs in these veins and as disseminations in the silica-carbonate rock. Bravoite and vaesite occur in some quartz-cinnabar veins.

The deposit is typical of many mercury deposits in serpentinite. It appears that serpentinite containing Ni, Fe, Mn and Al, when exposed to a solution of the composition of geologically related thermal springs can reasonably produce the silica-carbonate rock, veins and

Control of Flotation Recovery using Regression Analysis

The concentrator of Bonneville Ltd. at Wendover, Utah, processes a feed obtained by solar evaporation of a brine containing sodium and potassium chlorides with minor amounts of impurities. Salable potassium chloride concentrate is produced from this feed in two steps: flotation with amine reagents to concentrate the potassium chloride, and washing of the concentrate with fresh water to reach final grade. In the flotation step emphasis is placed on recovery, whereas the washing step has as its objective the production of salable grade (in excess of 60 percent K2O equivalent), with recovery being important but secondary.

If the process is arbitrarily divided into flotation and washing functions, there are a number of variables involved. Among those for flotation are:

while washing includes:

The over-all objective of this study was to utilize statistical techniques to achieve better understanding and control of the flotation operations. Only flotation recovery was considered. A separate study is being made on washing.

The data used in this study are from 276 consecutive shifts. The data were recorded once per shift and are assumed to be accurate; that is, no allowance for assay or other

Comminution in Brittle Solids Resulting from Hypervelocity Impacts

Comminution is an old art. Unfortunately the analysis of the unit operations has been handicapped by the lack of both theoretical and experimental information. Two types of information are needed, one an understanding of what happens when a particle breaks in a brittle manner; and two, an understanding of what happens when the daughter fragments pass through the mill.

Recently, successful theoretical attacks on the fracture of brittle solids have yielded significant results. New experimental techniques are yielding insight into the physical phenomenon occurring during brittle fracture. Many of the re-doubtable shiboliths of the last century are either being laid to rest or verified.

The problem with a shock wave is that, from its beginning to its decay into a compressive elastic wave we do not fully understand the dynamics. The shock wave proceeds into the target material as well as into the projectile material. The shock wave moves both perpendicularly into the target and the projectile. However a rarifaction wave originating at the edge of the material eats into the compressive shock wave, attenuating it.

Hypervelocity impacts are spectacular phenomenon. Material in the liquid state is ejected from the early crater at velocities exceeding that of the impacting projectile. Associated with the

Placer Gold Analyzer XRF

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Exploration of Alluvial/Eluvial Gold Deposits

The topic of this short information is the exploration of deposits of not consolidated (loose) gold bearing material with free

Merrill Crowe Laboratory Testing Procedure

Efficient Merrill Crowe precipitation of gold and silver is dependent upon the proper control of certain physical and chemical properties of the solution. The most important of these properties are listed below:

Suspended solids: such as ore slime and precipitates of calcium carbonate, with hydrates of aluminum, magnesium and iron, present in the pregnant solution before clarification. These combined solids should be completely removed by efficient clarification.

Suspended precipitates: as above defined, which may continue to form in the solution after clarification. This formation occurs slowly and is almost completely prevented by clarifying and precipitating simultaneously.

Scale forming compounds: mainly the carbonates and sulphates of lime.

Oxygen and carbon dioxide gases dissolved in the solution: these prevent efficient precipitation of the precious metals. The solution must be oxygen free.

Cyanide strength: a small amount of free cyanide is necessary to catalyze the zinc:gold reaction but as little as 50 ppm of free cyanide should normally be sufficient. This is only the case if the solution is relatively free from base metals like copper.

Alkalinity: normally the solution pH is already above 10 as a result of leaching. pH should be maintained at this minimum level.

Copper: excess copper will prevent the zinc:gold reaction as it preferentially precipitates

How to Recover Molybdenum in Oxidized Ore

A study of some variables affecting the recovery of molybdenum from oxidized molybdenum minerals was made. The effects of variations in contact time, temperature, pulp density, particle size, and solvent concentration on the recovery of molybdenum using acid and alkaline solvents were investigated. Chemical analyses, screen analyses and microscopic examinations were made and the presence of important elements determined.

Description of the Ore

Geologically, this ore occurs in the bottom of the Chadron formation sandstone at the disconformity between the Chadron formation and the Pierre shale. Hand samples of the mineral ilsemannite have also been recovered from this deposit. The rock is composed predominantly of silica sand. The bonding material contains the molybdenum minerals and the iron minerals hydrated and otherwise.

The ore sample was stage crushed through 6 mesh and mixed by recombining splits from a Jones riffle. Upon further sampling and analysis it developed that we could cut reproducible (± 0.01% M0O3) samples at 100 gms wt from our minus 6 mesh aggregate.

Experimental Work.

The first sequence of tests were run to determine the effect of roasting on molybdenum extraction. A series of samples was roasted for one hour at temperatures of 100°, 200°, 300° and 400° C

Power Scale-Up for Agitating Slurries

An interesting problem with which the senior author has been concerned with is the scale-up of power requirements for slurry agitators operating in the laminar region with pseudo-plastic materials. Pulps of shaly ores, after various chemical reactions in aqueous leaching systems, are often difficult to settle and filter if agitation is violent. In these cases agitation must be at a minimum, yet prevent tling such as in copper uranium ores. This mild agitation is on the laminar region.

The starting point of this investigation is the known relationships for agitating Newtonian fluids. The Reynolds number is a measure of similitude in agitation and is derived from the ratio of the internal reaction per unit volume of fluid (V²D) and a viscous force present per unit of volume (µV/D²).

For flow through pipes, this is:

RE = P V²/D/µ V/D² = D V P/µ

where: RE = Reynolds numbers
D = diam. of pipe
V = velocity
p = specific gravity
µ = viscosity

all in consistent units.

For agitation, velocity is the speed at the tip of the impeller. If N is agitator revolutions per second, then: π D N = V. Since π is a constant, the Reynolds number of agitation becomes:

RE = N D² p/µ

Tertiary Zeolite Ore Mineral Distribution in Size Fractions

Zeolite ores and protores occur in extensive deposits in the western United States. A recent paper describes the general geology and mineralogy of these deposits and their geographical distribution. The zeolites are alkali- and silica-rich varieties of mordenite, erionite, chabazite, phillipsite, ferrierite, and clinoptilolite.

The Tertiary zeolite ores consist of one or more zeolites (mordenite, erionite, chabazite, phillipsite, ferrierite, clinoptilolite) formed as alteration products of pyroclastics. In addition to unaltered volcanic glass the gangue minerals include quartz, cristobalite, tridymite, opal, feldspar, montmorillonite, hornblende, calcite, gypsum, thenardite, iron oxides, and in some cases one or two other zeolites. Removal of the silica minerals and glass is the main problem in ore beneficiation.

Mineralogical analysis of size fractions obtained on zeolite ore samples dispersed with minimal grinding provides a quantitative determination of the constituents, reveals the microtexture, and gives the size distribution of the single crystals and various types of aggregates and particles. These data are useful for beneficiation as they aid in the choice of the initial method of disaggregation and give the size ranges in which the zeolite and gangue minerals concentrate.

The bulk mineral compositions, as determined by analysis of the size fractions; abbreviations used are mordenite (MO), clinoptilolite (CL), erionite (ER),

Mine Drainage Control and Treatment

Standards vary from state to state for reasons which I find impossible to explain. For example, Pennsylvania has set an iron limit of 7 mg/liter (7 ppm) on the discharge from a treatment plant. West Virginia, on the other hand, has adopted 10 mg/liter (10 ppm) in the receiving stream as a satisfactory iron level, thus giving proper credit for the dilution effect of the stream. As you all know, public hearings are currently being held in all fifty states, attempting to develop stream standards which will be satisfactory to both the states and the Federal Water Pollution Control Administration. So, we still are aiming at a moving target.

Now, let’s consider the fate of the ferrous iron and the acid in the water as it moves—miles, in many cases—from its point of formation to its point of discharge. As all of you know, substantial amounts of limestone or calcium carbonate are associated with coal deposits.

The first reaction (Equation 1)—which occurs rapidly—is the reaction of the acid with, say, limestone. Bicarbonate ion is formed and acid in the mine water is neutralized.

After, or simultaneously with neutralization of the acid, another important reaction begins. You will remember that I stated that ferrous,

Use LIX-64 Extractant for Copper Pilot Plant Data

Design parameters for scale-up to commercial plants are presented and discussed along with a revised capital cost estimate. The future pilot program is discussed, including minor design changes and the effect of entrained organic on dump leaching efficiency.

Description of The Liquid Ion Exchange Process

In the extraction section, a water-immiscible organic solvent (normally kerosene) containing an organic extractant is contacted with an aqueous solution containing the metal to be extracted. The two phases are then allowed to separate. Interstage pumping of both organic and aqueous is accomplished by employing the mixer impeller as a pump. A variable number of mixer-settler stages and flowrates may be used to achieve the desired recovery and concentration of the metal from the feed solution. After removal of the metal values, the aqueous solution leaving the extraction section is referred to as the raffinate.

The organic phase containing the metal values (referred to as the loaded organic) is then transferred to the stripping section, where the metal values are transferred from the organic phase to an aqueous solution for subsequent treatment, and the stripped organic recycled to the extraction section.