Blogs
Precious Metals Refinery Security
“Highgrading” a polite word for stealing gold and silver for your refinery, has been a way of life since the metals in native form have been mined or produced. Unfortunately, in the past, highgraders were not always severely prosecuted or even looked upon unfavorably in their communities. Recent high metal prices with attendant world wide publicity, however, has made highgrading
Grinding Media & Lining Media Liner Wear Rate Modelling & Prediction
The cost of replacement of the metal worn from the working surfaces of the balls and liners of a mill often represents a considerable fraction of the cost of operation of the plant and so is of some real economical importance. In spite of this importance, however, the amount of information in available on this subject is amazingly small and, unfortunately,
Merrill Crowe Leach Solution Sampler
This keeps the leach sample secure prior to its assaying. A simple electric box, lock and key, piece of pipe, funnel, bottle and yes, some wire.
Grinding Process
In the previous chapter, the various “laws” of comminution which have been propounded have been studied in relation to the physical process of size reduction and to the available results of experiments into the fracture of homogeneous and heterogeneous materials by impact and by slow compression. In this study it is seen that no satisfactory “law” of comminution has yet
Comminution
The problems associated with comminution of solid bodies in numerous and complex. In spite of the large amount of investigation which has been undertaken, the present state of knowledge is such that there is no theory by means of which the behaviour during fracture of even a single particle under the simplest possible mode of loading can be predicted in reasonable detail
What Equipment Best Recovers Gold by Size: Fine to Coarse Particles
Many types of efficient placer gold recovery equipment are available today. The choices facing those designing a recovery system for a particular site are not easily made. A major consideration, of course, is cost versus recovery, but other factors must also be considered when designing an effective system. The size distribution of the gold is important because it will narrow
Spiral Wheel Gold Concentrator
An interesting variation of the spiral concentrator is the rotary table. This device is available from a variety of manufacturers under many trade names. Basically, the rotary table consists of a flat, circular plate in which a spiral pattern has been molded or cut. It is usually mounted on a frame with a wash water bar running laterally from the
Reverse Helix Gold Trommel
Another concentrator device based on the spiral design is the helix gold trommel. A helix is a cylinder lined with spirals along the inside. Helixes are suitable for use as roughers or cleaners, depending on their size. Sizes range from small 1 foot diameter by 5 feet long cleaners to large roughers 8 feet in diameter and 40 feet long
Pinched Sluice
Pinched sluices have been used for heavy-mineral separations for centuries. In its elementary form, the pinched sluice is an inclined trough 2 to 3 feet long, narrowing from about 9 inches in width at the feed end to 1 inch at discharge. Feed consisting of 50-65% solids enters gently and stratifies as the particles flow through the sluice and crowd into
Reichert Cone
The Reichert cone concentrator is based on the pinched sluice concept. If a number of pinched sluices are arranged side by side, with the discharge ends pointed inward, they will form a circular tank with each sluice forming an individual compartment. Removing the sides of each sluice forms a circular tank with an inverted cone for the bottom, a basic
DRY Shaking Air Table to Recovery Gold
Air tables use a shaking motion similar to that of shaking tables, but instead of water, air is used to separate heavy minerals. The table deck is covered with a porous material and air is blown up through the deck from a chamber underneath. The chamber equalizes the pressure from the compressor and thus ensures an even flow of air
Long Tom Sluice
The Long Tom is a sluice variant and as you would expect the LONG TOM and the dip box are included here because of their simplicity and potential usefulness. The long tom is a small sluice that uses less water than a regular sluice. It consists of a sloping trough 12 feet long, 15 to 20 inches wide at the
Gold Rocker Box Design
Rockers are widely used for washing placer samples and under most conditions they are well suited to the needs of the field engineer. It should be noted that since its inception, the American gold dredging industry has, for the most part, used rockers in preference to other types of sample washing equipment. The fact that the rocker has survived in
Placer Mining Methods
Here is practical, timely information on Placer Mining Methods and equipment used in placer gold recovery. Included is detailed information on equipment, practices, recovery factors, efficiency, design, and, where available, costs. Selected gold recovery operations are described in detail. In addition, the reported efficiency and reliability of various types of equipment used today is presented. One notable method not described is
Exploration Drilling Method: Setup, Operation Procedure
Table of ContentsDRIVING THE PIPEDRILLING OPERATIONSDRILLING PROCEDUREPUMPING OUT THE COREPIPE PULLINGPIPE PULLING WITH CASING SPEARTREATMENT OF DRILL COREMUD BOX OR DUMP BOXTHE VOLUME BUCKETTHE PANNING TABLETHE SAMPLE BOTTLESTHE ROCKERTREATMENT OF GOLDDRILL RIG LOG BOOK HILLMAN MULTIPLYING FACTORSFOR DETERMINING GOLD VALUE PER CUBIC YARD Setting Up The Drill: The drill is placed in the desired location for the hole, leveled, and the derrick
Grinding Media Charge Motion inside Mill
Table of ContentsTheory of von SteigerCascading MotionTheory of DavisCataracting Motion The motion of the charge, that is the grinding media and the material undergoing grinding, within a mill is of considerable theoretical interest and practical importance, and for these reasons, has been the subject of considerable study by a number of workers, but, even so, no rigid and complete theory, covering
Grinding Mills – Common Types
Table of ContentsWhy is Ore Grinding NecessaryBall millTube MillRod MillPebble MillBatch MillGrate Discharge MillTrunnion Overflow MillAir Swept MillsDry Grinding VS Wet Grinding In many industries the final product, or the raw material at some stage of the manufacturing process, is in powdered form and in consequence the rapid and cheap preparation of powdered materials is a matter of considerable economic importance. In
Alkali Consumption Tests
It is often desirable to ascertain by preliminary experiments the quantity of alkali which will be needed to neutralize acidity in any particular ore. In this connection a distinction is sometimes made between “ free ” and “ latent ” acidity. The free acidity is that due to substances soluble in water, and is determined by agitating a known weight
Density Determinatons
To find weight of a given volume of sand or similar material. In cases where it is not convenient to weigh the entire charge direct, the wet and dry weight of a charge is often ascertained by allowing a vessel of known capacity, say a large cubical or cylindrical box, to be filled at the same time and in the
Gravity Gold Process Water Requirements
The source, amount, and delivered cost of water are important elements in a placer operation. In many cases they determine the type of equipment or mining method used. Water estimates for new or proposed operations are generally based on experience or working data obtained from comparable operations. The water required for various working methods varies widely and depends on many
Organic Carbon TOC Pre-Flotation & Preg‐Robbing of Gold
Organic carbon is a common problem for base metal production and precious metal leaching. In froth flotation, liberated organic carbon is naturally hydrophobic and will be recovered with the other minerals, lowering the grade of the concentrates. It can also adsorb collectors and frothers, reducing the efficiency of the mineral recovery process. In leaching, the absorption properties can remove precious