| Term | Explanation | Editorials |
| CALCINE | Calcine A name given to concentrate that is ready for smelting and free of any unwanted substances. | Search Editorials |
| CALL FACTOR | Call Factor A term used to describe a part or fraction of an ore reserve that is successfully mined. | Search Editorials |
| CAPTIVE STOPE | Captive Stope A stope that has accessibility only through a manway. | Search Editorials |
| CAR | Car A small to medium railway wan used to carry ore and waste through underground tunnels. Can also be known as a passenger car for moving mine workers. | Search Editorials |
| CAR DUMP | Car Dump A mechanism used to unload a mine car. | Search Editorials |
| CARBON ADSORPTION | Carbon Adsorption A process in which soluble complexes of ld and silver physically adhere without chemical reaction to the molecular surfaces of activated carbon particles. The process is used to collect ld and silver from leach solution. The activated carbon is usually made from coconut shells. | Search Editorials |
| CARBON-IN-LEACH | Carbon-in-Leach Cyanide is used to dissolve ld from the ore into a ld/cyanide solution. Carbon is then used to absorb the ld from the solution and then the ld recover similar to the carbon-in-pulp process can take place. Picture courtesy of Rio Tinto & Placer Dome. J.V Project: Cortez ld mine Run-of-mine oxide ore is crushed and stockpiled before grinding in an autogenous mill and a ball mill. Discharge from the AG mill is screened, with screen oversize being conveyed to a cone crusher and recycled to the AG mill. Screen undersize and ball mill discharge are sized in hydrocyclones, the overflow being thickened to provide feed for the carbon-in-column (CIC) and carbon-in-leach (CIL) circuits. The CIL circuit consists of eight CIL tanks, 16 screens and eight carbon-forwarding pumps. Retention time at the 9300t/d throughput rate is 44 hours, increasing to 54 hours when milling South Pipeline ore at 7500t/d. The CIC circuit consists of six carbon columns with a retention time of 18 minutes. After stripping the carbon using a pressurised Zadra process, the ld is recovered by electrowinning on to stainless steel wool cathodes. The filter cake is dried, melted in an induction furnace and poured into dor? bars assaying approximately 90?94% ld and 3?6% silver for shipping to commercial refineries. | Search Editorials |
| CARBON-IN-PULP | Carbon-in-Pulp A recovery process in which a slurry of ld ore, free carbon particles and cyanide are mixed together. The pregnant solution is passed counter current through a series of tanks containing activated carbon particles. ld has a natural affinity for carbon and the carbon absorbs the ld as it passes through the circuit. The sequence of ld extraction from ore by the carbon-in-pulp process now widely used in Australia and the United States, particularly in open-pit operations. Loaded carbon is removed from the slurry by screening. The loaded carbon is stripped in a caustic cyanide solution under heat and pressure prior to the recovery of the ld by electrolysis or by zinc precipitation. The carbon is treated for re-use. Carbon Adsorption In Recovery Of ld From Cyanide Leach Solutions It has been known that ld in a cyanide leach solution would adsorb to activated carbon for over 70 years, and many papers have been written on the subject. Carbon, as a media of recovery for ld from leach solutions, did not gain wide acceptance in the ld industry until the 1970's, with the explosion of heap leaching of vast quantities of low grade ld ores, and subsequent production of many gallons of pregnant leach solution. It is now the most common method used for the recovery of ld from a cyanide leach solution. Two primary methods, Carbon In Pulp (CIP) and Carbon Columns probably comprise the most widely utilized techniques for extracting ld, now days. In CIP, the carbon is mixed with the cyanide leach solution, and agitated in the leach tanks, and agitated with the ore while the ld is being dissolved. This assures a rapid interface between the carbon and the ld loaded cyanide solution. Granular, hard carbon is used, in the size range of 10-16 mesh. The carbon is then removed by screening, across a carbon screen, allowing the liquid and finely ground ore (-100 mesh) to pass through easily, and retaining the carbon on the screen. The carbon is then generally subjected to a heated solution (200 deg to 250 deg F) of (1%) sodium hydroxide and (0.1%) cyanide and the ld is re-dissolved and removed from the carbon surface. At this point, the NaOH/CN solution is sent to electrowinning cells, where the ld is plated onto stainless steel cathodes. The ld is removed from the cathodes by either using a high pressure water spray, sometimes shaking the cathode, and in some cases, the stainless steel cathode is placed into a melting furnace and heated to 2,000 degrees F, to melt the ld from the cathode. The stainless steel cathode, of course, does not melt at this temperature, but such temperatures reduce the life of the cathodes, and most will wash the ld "sponge" from the cathodes. The fine, powdered ld is then melted and poured into dore bars. The carbon in pulp method is only used where tank leaching is utilized for the recovery of ld from the ores and this is not the case in most large ld mines today, since heap leaching is the lowest cost method for recovering ld from ores containing from a few grams to 5 or 6 grams per ton. If the ore is a high grade, it may be feasible to tank leach it. By high grade, it would probably be in the range of ? ounce per ton (Au) range or greater. The cost of leaching by tank is considerably greater than leaching in a heap. This is due to the requirement to crush the ore to -100 mesh (at least), and to provide mechanical equipment to store and agitate the ore for extended periods of time (4-6 hours). Occasionally, carbon columns will be used with tank leaching operations, also, especially if the mine has a dual leach system, heap leach of low grade and tank leach of high grade. Carbon columns consist of large columns (5 to 8 ft diameter) and 15 to 20 feet in height, charged with activated carbon. The minimum load of carbon rule of thumb is one pound of activated carbon per 0.1 ounce of ld present in the solution. Usually, it is several pounds per 1/10 ounce, though, as the cost of carbon is relatively insignificant compared to timely recovery of ld. The pregnant cyanide solution flows through the carbon columns, which are generally situated in step fashion, so that the overflow from the highest column will gravity flow to the next column, alleviating the requirement for pumping. The ld adsorbs onto the surface of the carbon. The loaded carbon is periodically removed from the columns, and sent to the stripping circuit. The carbon is then generally subjected to a heated solution (200 deg to 250 deg F) of (1%) sodium hydroxide and (0.1%) cyanide and the ld is re-dissolved and removed from the carbon surface. At this point, the NaOH/CN solution is sent to electrowinning cells, where the ld is plated onto stainless steel cathodes. The ld is removed from the cathodes by either using a high pressure water spray, sometimes shaking the cathode, and in some cases, the stainless steel cathode is placed into a melting furnace and heated to 2,000 degrees F, to melt the ld from the cathode. The stainless steel cathode, of course, does not melt at this temperature, but such temperatures reduce the life of the cathodes, and most will wash the ld "sponge" from the cathodes. The fine, powdered ld is then melted and poured into dore bars. Any silver present in the ore, will also be leached in the cyanide solution, and will be present in the dore bar, as well. Most mines do not have the refining capacity to separate the silver from the ld and the bars are sent to a commercial refinery for producing the 99.99% ld and silver ints that are sold on the commercial ld market. Once the carbon has been stripped, it can be reused after recharging it in a kiln, by heating it to around 1300 degrees F. The carbon is then cooled, screened to remove fines and is ready for reuse. Fines are not desirable in carbon circuits, since they will escape through the carbon screens and end up in the leach, capturing ld that will not be recovered. For this reason, high quality and hard carbon is generally utilized for these applications. Generally, the size range of the carbon is 10 mesh to 16 mesh and almost always no finer than 20 mesh. Coconut shell carbon is generally the preferred carbon for use in recovering ld from leach solutions. source: www.pamp.com back to top | Search Editorials |
| CASH PRODUCTION COST | Cash Production Cost | Search Editorials |
| CASTING | Casting The basic process of forming a shaped article by pouring and solidifying molten metal in a mould, which has many variations in ld. In the manufacture of ld bars, it distinguishes between those cast in a mould (such as od-delivery-bars or kilobars) and small bars which are stamped out of a metal strip. Continuous casting allows a constant shape to be withdrawn from the bottom of a mould as the metal solidifies so that semi-finished products such as strip and tubes can be produced. | Search Editorials |
| CHANNEL SAMPLE | Channel Sample A channel is cut to a specified dimension (LxWxD) in exposed rock to provide a sample for assay, to determine the quality of the ore. Geologist looking on while channel sample is taken. Photograph courtesy of Cabo Mining Enterprises Corp | Search Editorials |
| CHANNEL WIDTH | Channel Width The overall thickness of several closely spaced layers of reef, including internal waste, particular to South African ld operations. | Search Editorials |
| CLAIM | Claim To stake a 'claim' is the acquisition of land for exploration or mining where a vernment lease or licence is granted when a claim is accepted. The Australian term for claim is 'pegging'. The process of acquisition of land for exploration or mining varies throughout the world. The process can involve the netiation of agreements with existing private owners, the outright purchase, the staking of lands, or acquisition from the vernment of these rights under a licence or other form of permit. Environmental regulation may restrict licensing and can lead to delays of five years or more in obtaining provisions. In the United States, mineral rights pass with the surface estate and consequently many mineral deposits are privately owned. Lease areas or claims can also be staked and maintained by working the project and subsequently title to the deposit and surface estate can be acquired. In Canada, the right to explore or mine is granted according to each provincial mining act but in general the mineral estate is severed from the surface estate. In British Columbia, for example, rights to mine ld from a claim area are acquired in the form of either a placer lease or a mineral lease. In Australia, all ld mineral rights are vested in the Crown, with the individual state vernments granting mining rights. A miner?s right is usually sufficient to explore Crown lands, although further approval is required for private lands. The situation has been complicated by the Native Title Act of 1993 which confirmed the right of aboriginal people to apply for title to land. The act takes precedence over the Australian Mining Act of 1978, except where a full mining lease has already been granted. An exploration lease can be invalidated by subsequent claims of native title. In South Africa, mineral rights and prospecting rights in respect of precious metals are granted by the vernment. The vernment may grant a prospecting or mining lease for consideration of a lease payment. | Search Editorials |
| CLARIFICATION | Clarification A filtering process to remove suspended material from dirty water. | Search Editorials |
| CLEAN-UP | Clean-up Clean-up is the process of reclaiming any economical ld accumulated around a production plant of any remaining in-ground deposit around the operation when a mine comes to the end of its working life. Clean-up (in non mining terms) can also mean the re-claiming of the land at the end of a mining process when the ore in the ground has been depleted. Once the mine has closed, the land can then be reclaimed into a National Park, lakes etc, with the re planting of trees. | Search Editorials |
| CM-G/T | Cm-g/t A concept used in South African ld mines for comparing the value of the ore body with that of the other mines or working places. It is calculated by multiplying the width of the reef (in centimetres) by the grade (grams per ton) over that width. | Search Editorials |
| COLLAR | Collar term used to describe the entrance, or mouth, of a mine shaft. sually made of timber or concrete, it could also be used to describe the top of a drill hole. Construction of collar - first stage of building a mine shaft. | Search Editorials |
| COLOURS | Colours | Search Editorials |
| COLUMN FLOTATION | Column Flotation milling process that uses a tall cylindrical column to separate valuable or unwanted minerals from the gangue. | Search Editorials |
| COMMINUTION | Comminution term for breaking, crushing or grinding of rocks or ore. | Search Editorials |
| COMPETENT ROCK | Competent Rock ery strong rock that is capable of supporting openings without the use of any structural supports, except for walls and rock pillars. | Search Editorials |
| COMPLEX ORE | Complex Ore An ore which contains a number of different minerals, however it could be uneconomical to extract all the minerals from the ore and a focus on the main mineral is the only option. An example of complex igneous rocks with veins of pink syenite cutting gabbro. www.turnstone.ca/ | Search Editorials |
| CONCENTRATE | Concentrate powdery product of high grade valuable ore which has had the majority of the waste removed. ncentrate stockpile | Search Editorials |
| CONCENTRATOR | Concentrator A particular type of milling plant process that produces a concentrate of ore. | Search Editorials |
| CONE CRUSHER | Cone Crusher machine that has a gyrating cone or crushing head that crushes and reduces the size of ore produced from the mine. ee als crusher/crushing | Search Editorials |
| CONGLOMERATE | Conglomerate A sedimentary deposit of pebbly or quartz fragments that have been compressed and bonded together with a mixture of finer material. A od example is the Witwatersrand stile paleoplacer deposite. The Klondike area may have been completely covered by conglomerate. An example of a 'conglomerate' picture courtesy www.aradon.com.au/ | Search Editorials |
| CORE | Core A core or core sample is a long cylinder of rock made usually during exploration work where a diamonddrill is driven into the ground at specified depths. The core can be examined for traces of minerals, and a number of core samples can produce a three dimensional image of an ore body in the ground. Core samples from Burkina Faso. Core sample www.orezone.com/ www.saskmining.ca/ | Search Editorials |
| COUNTRY ROCK | Country Rock A loose term used to describe the general mass of rock adjacent to an ore body, as distinguished from the vein or ore deposit itself. | Search Editorials |
| CROSS-CUT | Cross-cut A tunnel mined horizontal but cuts across or through the ore body or strike. | Search Editorials |
| CRUSHER/CRUSHING | Crusher / Crushing picture courtesy www.mine-engineer.com/ Jaw Crusher Cone crusher or Gyratory cone crusher Side view of working Gyratory crusher Photograph courtesy www.mining-technology.com/ icture courtesy 'Hebei Machinery & Equipment Corporation' Pendulum-type ring- roll Pulverisers. | Search Editorials |
| CUPELLATION | Cupellation In the fire assaying of ld, the sample being tested is placed in a small crucible, or cupel, (made of bone ash) in which it is heated with lead. The lead and any base metals are oxidized and absorbed into the cupel, while ld, together with any silver, remains as a metallic button. | Search Editorials |
| CUT-AND-FILL STOPING | Cut-and-fill Stoping This is a mining method used when there is an ore body with a steep gradient located under difficultwall rock conditions. The ore is drilled and blasted, then extracted in upward advancing slices. The vacant area left by removing the slice is then filled with material, providing support to the mass of rock adjacent to the ore body. | Search Editorials |
| CUT-OFF GRADE | Cut-off Grade The lowest grade of ore at which it is profitable to mine, usually at the edge of an ore body or when the ore body is depleted. | Search Editorials |
| CUT VALUE | Cut Value calculation that is made to provide a balanced or mean value of the ore body, as there will never be a consistent g/t (grams per ton) throughout the extraction of ore body. roduction will rise and fall depending upon the concentration levels of ld throughout the ore body. This calculation can also be adapted for high grade, samples and assays. | Search Editorials |
| CYANIDE/CYANIDATION | Cyanide / Cyanidation Cyanide is an excellent medium for removing ld from the ore. ld naturally dissolves into cyanide-like sugar in hot water and has become the primary method used, especially for low grade ld producers. The MacArthur-Forrest Process (est. 1887) pioneered the the use of cyanide, which has largely replaced the amalgamation process using mercury. Cyanide is a very toxic chemical and mining companies take great care in its use and recycle cyanide within their processing plant. Cyanide can be devastating to the local environment when leaked into streams and rivers. esponsible mining companies therefore take the issue of cyanide very seriously. | Search Editorials |