Time and Stratabound Ore Deposits:

Native copper
Photo by Rob Lavinsky

Time and strata bound ore deposits are formed because of a specific geological event that causes the deposition of ore.  This ore is not necessarily deposited at the same time as the rocks, but can be the result of a later infusion of metal bearing liquids with a chemical reaction depositing the metals from solution.  A typical reaction may occur between the solution and organic components in the host rock.

Another type of time and Stratabound deposit is volcanogenic massive sulfides.  These deposits are the result of metal sulfides being the first minerals to form in a magma, and sinking to the bottom of the magma chamber due to their higher density over the other components of the magma.

A common form of this kind of ore deposit is one that forms where there is a fossilized log jam in the bed of a paleostream deposit where the logs provide a large bed of organic matter that can be replaced by later mineral bearing fluids. 

These fluids are generally the result of volcanism, and are coming from both groundwater sources and juvenile waters that are expelled from the magma as it cools.  These waters can also dissolve metals from the surrounding country rock as they are passing through then.  The majority of ore deposits are of this type.

Another type of Stratabound deposit occurs when you have a paleo-karst terrene where the mineral laden waters follow the overlaying sediments that are usually sandstone that has also filled the nooks and crannies in the karst terrene.  An example of this is the lead/silver deposits that were mined in Leadville, Colorado.

The presence of petroleum can also supply a source of organic materials to trap metal bearing solutions and make them give up their riches.  This usually happens in volcanic intrusions into sedimentary rocks that produce enough heat to turn some of the petroleum into an analog of amber called “Pyrobitumen.”  This often happens in back arc basins like the Sea of Japan.

The metals are usually deposited anywhere they meet with a reducing environment.  A back arc basin is one of these places.  A marine basin is another of these places, and a good modern example is the Mediterranean and Black Seas.  Other then the mane made Suez Canal this large area of seawater only has one natural entrance and exit the Straits of Gibraltar.  The waterflow is restricted through these straits due to their narrowness, and shallowness.  The waters from the Atlantic flow inwards along the bottom, and the water from these seas flows outwards from the top.

Most of the world’s ore deposits are found in Time and Stratabound deposits. 

References:

Maiden, KJ, et al, Regional controls on the location of Stratabound copper deposits, Science direct, abstract, http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBP-48B5BVS-9&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1129894181&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=f1dc9cf34b161c53f88e513d56418aca

Cisternas, M. Eugenia, et al. The role of bitumen in Stratabound copper deposits in the Copiapo region of Northern Chile, Springerlink, http://www.springerlink.com/content/c445014g82520508/  

The uses of Pumps in Mines

A pump is a mechanical device used for transferring fluid from one point to another. There are several different varieties of pumps that are found in the marketplace, but the most common in use are the centrifugal pump and the piston pump. The most common pump in use now is the centrifugal pump although in the past the more common variety of pump was operated with Pistons. The primary use for pumps in the mining industry is for the removal of groundwater that seeps into the mine from the surrounding strata.

This is a Cornish piston pump used in the 19th century to pump water from a mine.

In some mines the order is reduced to a powder that is mixed with a fluid allowing it to be pumped as a slurry. Other pumps are used to supply power too hydraulic units that are attached to various types of mining equipment.

No matter what its use; pumps require an external power supply that used to be supplied by steam, but is now replaced by diesel. In many cases the motive power for operating a pump is supplied by electricity this is especially true of the smaller pumps that have electric motor attached correctly to the shaft of the pump.

A cutaway view of a centrifugal pump.

Pumps are also used in various hydrometallurgical processes used to separate ore from gangue. This is illustrated by their use in flotation cells for separating sulfide minerals from the surrounding rock. In other cases pumps are used in the heap leach method of recovering gold with a solution of cyanide. In this case the pumps pressurize a cyanide solution forcing it out through nozzles where is allowed to seep down through the heap of crushed ore where it is collected in a sump at the bottom of the heap to be recirculated through the heap several times until the solution becomes pregnant with gold.

The pregnant solution is then drawn off, and the gold or other metal values are removed by reacting to solution with a powdered metal such as zinc to precipitate the gold that is then taken to a refinery for further processing.

In alluvial or placer mining centrifugal pumps are also used in several places notably in supplying water to sluice boxes or hide bankers. They are also used in the operation of a suction dredge for the removal of mineral laden sand and gravel from the bed of the stream. In larger gold dredges they are actually used to process the gold bearing sand and gravel.

A gold dredge in operation in Nome, Alaska.

 As you can see there are many uses for pumps in the mining industry, and because man is an ingenious creature he keeps developing more!