Test drilling for gold is an important step in prospecting and eventually commercially mining for gold. Test drilling is done to get a continuous sample of the bedrock of a given gold project. The sample is then tested to determine if there is gold in the project area and to estimate the amount of gold that can be mined in the area. Quite often test drilling may produce a variety of result as each hole may encounter different types of rocks and soils, however, it is the most effective method used to estimate the amount of gold ore in a given deposit.

Drilling is an absolute necessity to evaluate metallic ores prior to expanding into a full-scale mining operation. Drilling can be done for any large scale mining operations, such as prior to the development of an open pit mine, or even for evaluations of large commercial placer mines.

Preliminary Prospecting Works

Before test drilling for gold is done it is important that some preliminary prospecting works are done. Quite often the area to be test drilled may have bushes, difficult terrain or any other hindrances that may affect the result of the test drilling. It is thus important these are dealt with first. One of the most important preliminary prospecting works that may be done is trenching. This helps reduce the amount of top soils on areas to be drilled and thus helping make the test drilling to be effective.

Test drilling

Test drilling for gold is meant to determine whether there is gold in an identified gold field. It goes further to help and estimate the amount and grade of gold on the site. Test drilling may also provide important information on the general geology of a prospective mine such as the structure of the rock formations, the geochemical structure and the information on other minerals present.

The pattern of test drilling, the spacing and the number of the test drill holes is determined by the geometric orientation of the drilling site, the geochemical composition of the area and the distribution of the target mineral. For most scale test drilling the site is often gridded out into small grids that determine the number of holes to be drilled. Sometimes drilling is done following land formation such as rifts, river basin or even valleys.

In most tests drilling for gold speed and cost are important factors that are considered by the geologists. If the preliminary prospecting works were done successfully then a more accurate and perhaps most extensive drilling method may be used. Some of the most common test drilling methods that you can use includes hand drilling, rotary drilling, percussion drilling and diamond drilling. The type of drilling determines the equipment to be used.

Hand Drilling

This is done for small operations in on a small site. Hand drilling is done using small hand held drills such as sample tubes and augers. These drills cannot penetrate bedrock and thus are quite limited in their application. Today there are a wide variety of powered hand tools that can be used for hand drilling. However, this still limits hand test drilling for small scale gold mining.

The benefit of hard drilling is the reduced cost compared to larger methods, and this may be the best method for individual prospectors who lack the resources for larger exploration.

Percussion Drilling

This kind of test drilling is perfect for places where ones want to get samples in bedrock up to 10 feet. Percussion drilling is done using compressed air drills and this makes it much stronger than hand drilling. There are also large air drilling equipment that can be used in complex places.

Rotary Drilling

This kind of drilling is relatively easy and in expensive in a wide range of conditions. The process employs rigs and air compressors to drill holes in any condition. With proper tools and skilled manpower this kind of test drilling takes the least time of all the available trilling. The drills can get samples from between 20 and 100 feet holes.

Also Read: Mercury Amalgamation and Fine Gold Recovery

And: Commercial Placer Mining in the United States
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Diamond Drilling

This is the most versatile test drilling method that you can use. The machines used for this kind of drilling gets the most superior samples as they can drill deep and at any given angle and conditions. In most case drills used here may be powered by electric motors, gasoline, diesel and even air. The method can however be slow and quite expensive due to its complexity and thus it is only used for complex projects that require extensive drilling.

Importance of Test Drilling for Gold

The importance of prospecting prior to expanding a mining operation cannot be understated, and test drilling is one of those methods most commonly used for sampling. Although costs can be expensive, it takes some of the risk and guesswork out of the mining process and gives predictable estimates as to how much gold may be present in an area.