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Mining
Sept 3, 2004 9:53:24 GMT -5
Post by azesm on Sept 3, 2004 9:53:24 GMT -5
Link: thediamondhunter.com/learningDiamond Formation and Mining Deep within the earth's crust, a diamond is formed under terrific heat and pressure from soft, black, worthless carbon. This carbon becomes the hardest of all know substances...the diamond. Created more than three billion years ago and thrown to the earth's surface through volcanic eruptions in what is called kimberlite. Most of the radiant diamonds worn today are more than 100 million years old. Diamonds in volcanic, kimberlite pipes are said to be from primary deposits. Those that are found on the surface of the earth that were washed away from the immediate volcano site are called alluvial and are said to be found in secondary deposits. Mining Primary Deposits Kimberlite pipes are studied thoroughly to help anticipate yield. Also, the location and climate are considered. Kimberlite pipes occur in clusters, which have typically averaged 6-40 pipes per cluster. Each cluster can cover an area from a radius of 10 km to over 75 km. Kimberlite pipes have never been found in isolation. Kimberlites are on average 50 meters in diameter (though they can be as wide as 1,500 meters) on the surface, and can reach a vertical dimension of over two kilometers. These pipes are formed when gas-rich magmas passing through the Diamond Stability Field carry the diamonds to the surface, where they cool down and preserve their original crystal form. The cost of mining pipes is very high. Most of the time all the needs of the mining crews have to be brought in from miles away through difficult territory. It is time consuming and dangerous. Frequently the politics of the area are involved. The planning can take months and occasionally years. Once located and proven reliable though, mining a site can continue for decades. Approximately 23 tons of kimberlite has to be processed to get about 4 1/2 carats of diamond material. Only about one carat is of gemquality and the final yield after cutting is about 1/2 carat. So when you are looking at a 1/2 carat well cut, fine quality diamond you are seeing the results of quite a lot of expertise, labor and risk.
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Mining
Sept 3, 2004 9:53:53 GMT -5
Post by azesm on Sept 3, 2004 9:53:53 GMT -5
Open Pit Mining The mining of a pipe starts with the open pit method. The surface of the pipe is excavated in layers creating a series of steps (or benches). These steps are used as roads which circle down into the crater that grows deeper and wider during the process of excavation. When the crater becomes so deep that it is inaccesible to the proper equipment then underground mining begins.
Underground Mining This phase of mining requires the sinking of a vertical shaft parallel to the kimberlite. This shaft is used to transport equipment to the work areas and for the removal of the diamond ore. Tunnels are dug from the shaft into the diamond bearing kimberlite. There are a number of different methods used to actually extract the ore from the tunnels. The process of underground mining is much more complex and dangerous than any other type of diamond mining.
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Mining
Sept 3, 2004 9:54:22 GMT -5
Post by azesm on Sept 3, 2004 9:54:22 GMT -5
Stages in Diamond Exploration
Target : Primary diamond deposits: kimberlites (or lamproites, much less common)
Preliminary stage - few weeks Area selection: Diamond-bearing kimberlites tend to be located on Archean cratons, unaffected by any Major tectonic event or granitisation for at least 2,5 billion years. Extensional fracturing, extensions of oceanic transform faults, hotspot tracks, cover of the craton by horizontal sedimentary layers can all be favourable, as is limited previous exploration activity for diamonds.
Stage 1 - 6 to 12 months Regional survey, using airborne geophysics or regional indicator mineral sampling. Purpose is to find in large cratonic areas, covering several 10,000 square km, magnetic anomalies or indicator mineral trails that may lead to kimberlites. Initially a kimberlite province might be detected of say 30 by 30 km in size.
Stage 2 - 1 to 2 years (depending on number of targets found) Detailed ground follow-up of magnetic anomalies and indicator mineral trails by ground magnetics, closely spaced indicator mineral sampling, drilling and trenching, in view of discovering the individual kimberlite pipes in the kimberlite province.
Stage 3 - 3 months After the discovery of a kimberlite pipe, initial samples are sent for microdiamond content and indicator mineral composition to assess possible diamond content and then study of the size distribution of the microdiamonds and extrapolate toward the grade of commercial-sized diamonds.
Stage 4 - 6 months If microdiamond results are promising, bulk testing of the kimberlites is undertaken to assess the grade of the commercial-sized diamonds and their average value.
Stage 5 - 3 months If average value content seems better than US$ 40/tonne and near-surface tonnages exceed several million tonnes, start pre-feasibility study, with more drilling, delineation drilling, geotechnical drilling and more bulk sampling to firm up tonnages, grade and value (resources) estimates.
Stage 6 - 6 months Full feasibility study and permitting (environmental, legal, etc.), with detailed mine planning
Stage 7 - 2 years Mine and plant construction, infrastructure works
Stage 8 -4 to 6 years from the initiation of exploration, production should start-up.
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Mining
Sept 3, 2004 9:55:27 GMT -5
Post by azesm on Sept 3, 2004 9:55:27 GMT -5
Exploration Methods The exploration for diamonds involves significant budgets, technical experience and expertise in several fields, such as heavy mineral sampling and processing, mineral identification, indicator mineral chemistry, glacial geology, alluvial deposits, tectonics, large scale geophysics, structural geology, petrology, chemistry and geophysical techniques. All these fields are becoming increasingly sophisticated as diamond exploration activities evolve. To find Canadian kimberlites, it is necessary to combine the results of the chemistry of mineral indicators, regional ice advance and retreat pattern knowledge, and geophysical analysis. Because the potential area is quite large, the search for kimberlites is a very slow process. Following the ice advance and retreat patterns Most of Canada has been eroded out by a succession of ice sheets during the last 1.5 million years. All phases of ice flow contributed to the erosion of kimberlites and dispersed debris, including the diamonds, well beyond their source. Flowing ice is not restricted to drainage basins, and ice flow may change directions dramatically. Each advance of the glaciers affects the debris left by the previous one. It is necessary to identify which glacial advance transported particular material. Tracing Indicator Minerals The indicator mineral technique is based on recognition of distinctive minerals associated with the diamond source rocks. Indicator minerals are used to locate kimberlites rather than trying to find the source, because it is easier to follow the trail of indicator minerals. Mineral indicators are far more abundant than diamonds in a kimberlite, have visually and chemically distinct characteristics, and are more recognizable. They survive long distance transportation and they are resistant to weathering. When indicator minerals are found in glacial sediments that indicate the presence of a kimberlite, to a certain extent, give an evaluation of the potential presence of diamonds. The following lists the indicator minerals most commonly used in diamond exploration. Cr-pyrope (purple colour) Cr-diopside (emerald green) Mg-ilmenite (black, conchoidal) fracture) Olivine (pale yellow-green) Chromite (reddish-black, irregular to octahedral crystal shape) eclogitic garnet (orange-red) In a rare case, diamonds if they are abundant enough. Materials sampled are the medium to very coarse sand-sized fraction of glacial and glaciofluvial sediments, such as tills and eskers, alluvial sediments, soils and eolian sediments. Selected mineral grains are analyzed with an electron microprobe to determine the identification and chemistry of the indicator minerals present. The surface morphology of each grain can provide clues to the distance they traveled, and their mean of transportation. In several cases, the sediments have been subjected to repeated glacial transports, interglacial and occasionally, pre-glacial fluvial transport. This adds to the difficulty of tracing the elements to the source. atlas.gc.ca/maptexts/subtopic_texts/english/historical_e.html
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Mining
Sept 3, 2004 9:56:10 GMT -5
Post by fastwalker on Sept 3, 2004 9:56:10 GMT -5
;D Nice find AZ...Will you add it to the DD--informational section? could be a good source for review ..when we start open pit mining...
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Mining
Sept 3, 2004 9:56:31 GMT -5
Post by azesm on Sept 3, 2004 9:56:31 GMT -5
Location of Magnetic Anomalies Magnetic surveys measure slight changes or perturbations in the earth's magnetic field, the force that aligns a compass needle. These perturbations are anomalies compared to the surrounding areas. Magnetic anomalies can indicate the presence of kimberlite pipes, particularly when the overall study area presents a uniform magnetic field. The geomagnetic signature of a kimberlite is not unique, but is distinctive. In the Canadian Shield, kimberlites often present a circular anomaly. This anomaly can show a high contrast, low contrast, or no contrast at all with respect to the surrounding magnetic field. The contrast of the magnetic response of a kimberlite pipe with the surrounding rock is dependent of the remanent magnetic field of the pipe. The mineralogy of the pipe can also have an effect on the magnetic signature. The rock that composes the kimberlites is less resistant to erosion than the surrounding rock, so kimberlites tend to be more affected by erosion than the surrounding rock. This creates depressions over the kimberlites. These depressions are later covered by glacial material or filled by water, which makes kimberlites difficult to detect. The geophysical studies, such as changes in the magnetic field, play an important role in the detection of buried kimberlites. In the Lac de Gras area for example, geophysical methods have been very useful in the detection of kimberlites located under lakes. atlas.gc.ca/maptexts/subtopic_texts/english/historical_e.html
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Mining
Sept 3, 2004 9:57:11 GMT -5
Post by azesm on Sept 3, 2004 9:57:11 GMT -5
Evaluation of the Diamond Content of a Kimberlite Kimberlites are not all diamond bearing or economically viable. When a kimberlite is found, it is necessary to evaluate its diamond content: concentration (carats per ton), the size of the deposit, and also, the size and the quality of the diamonds. These two last characteristics are important to know because in the diamond mining industry, the product is valued in term of individual pieces. In a kimberlite, there is a relationship between the quantity of diamonds and the abundance of fragments from the mantle host rock where diamonds form. To determine diamond content, tons of rock are collected from the top of the pipe and processed. If diamonds are found, drilling and petrological examinations will give the extent of the deposit and information about the diamond content. Between 5 000 to 10 000 carats of diamonds are needed to fully evaluate a deposit. A diamond concentration that would allow an economic development of a mine would be around 0.5 carat per ton; a very good one would be in the range of 2 to 4 carats per ton. The distribution of diamond size and quality also need to be determined to be able to select a development strategy like surface excavation or underground mining. atlas.gc.ca/maptexts/subtopic_texts/english/historical_e.html
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Mining
Sept 3, 2004 10:43:12 GMT -5
Post by azesm on Sept 3, 2004 10:43:12 GMT -5
fastwalker
A pipe in the swamp..what is a swamp? « Thread started on: Sep 2nd, 2004, 10:06pm » <br>FYI ...INFORMATIONAL ONLY...
What is a Saskatchewan "Swamp"? « Thread started on: Today at 8:33pm »<br> -------------------------------------------------------------------------------- What is a Saskatchewan "Swamp"?
I thought with all this talk about the swamp I would try to clarify exactly what these "swamps" really are. There are referred to by farmers as sloughs in Saskatchewan (pronounced slews)
Here is a dictionary definition of a slough.
1. A depression or hollow, usually filled with deep mud or mire.
Keep in mind that a swamp in Saskatchewan is not the same as a swamp in Florida. My family farmed in Saskatchewan since the late 1800's and will try to relay my experience with sloughs.
A “swamp” in Saskatchewan is more like a grassy depression with a soft, moist top soil. This is usually because it is a low lying area that spring runoff accumulates and is allowed to soak into the ground. The ground becomes so saturated with moisture the ground become extremely soft and muddy. Even large 4 wheel drive tractors sink up to the axles and get extremely stuck. (I know because I have done it!)
These sloughs can be successfully dried out. Many farmers do as such and end up using them as producing crop land. The drying out basically means dredging a canal to allow the spring runoff to drain out of the low area into an adjacent low lying area or nearby ravine or creek. The dredging is usually done in the late summer when the conditions are as dry as possible. This provides a path for the spring melt to exit the area to prevent water accumulation and excessive moisture saturation. In the following summer once it is dry enough the sloughs are plowed in with dozers which push the bush and heavy grasses into windrows for burning. A root rake is then used to clear the area of roots that could potentially damage plows. It is then plowed many times to break up the grasses and soil into usable crop land. This also help dry out the lower layers of soil.
This then allows a farmer to plant a crop the following spring. Drying of a large slough can take around 18 months from the point of digging a canal to seeding a new crop.
However, not all these steps would be necessary to create a location suitable for mini-bulk or bulk sampling. A canal could be dredged in the fall and equipment could work through the winter clearing the bush and grasses. However, the ground is literally rock hard due to the winter freeze so it may be more appropriate to wait until the following summer to begin clearing. Remember that area can get as low as -30c and lower for long periods of time.
Basically within a year a slough can be transformed from a soft, spongy, unusable area into dry land bustling with diamond exploration activities.
As a side note given that fact that large kimberlight pipes are generally found in depressed areas, this slough is a good indicator of what may be hiding below.
Now you understand why..we have to drill on it when it is FROZEN..lol..
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Mining
Sept 3, 2004 10:44:00 GMT -5
Post by azesm on Sept 3, 2004 10:44:00 GMT -5
stevpot99
Re: A pipe in the swamp..what is a swamp? « Reply #1 on: Sep 2nd, 2004, 11:29pm » <br>
its also called muskeg in witch is basically peat moss
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Mining
Sept 3, 2004 10:45:24 GMT -5
Post by azesm on Sept 3, 2004 10:45:24 GMT -5
saturn48021
we need a geologist for this
« Thread started on: Sep 1st, 2004, 03:05am » <br>http://www.ir.gov.sk.ca/adx/asp/adxGetMedia.asp?DocID=4106,4038,3442,3440,3385,2936,Documents&MediaID=7165&Filename=mcneil.pdf
Will this give us any hint of what is in the area.You need a pdf to read.Was kind of boring to me because I don't know what they were talking about,sorry.
Saturn
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Mining
Sept 3, 2004 10:49:35 GMT -5
Post by azesm on Sept 3, 2004 10:49:35 GMT -5
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Mining
Sept 14, 2004 16:03:30 GMT -5
Post by azesm on Sept 14, 2004 16:03:30 GMT -5
saturn48021
Full Member
changes to mining disclosure rule « Thread started on: Today at 3:49pm » <br>http://www.bcsc.bc.ca/news/NR04_38-CSA.asp
Newest changes to the mining rules
Saturn
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