Gold Prospecting Methods - Types of trenching

Gold Prospecting Methods
- Types of trenching

Hand-Dug Excavations: These may be pits, trenches, or shafts and are suited to dry, shallow ground. This method of sampling is not used much today due to the high cost of labour but it can be effectively used in remote parts of the world where trained labour is not available, or general cost of labour is relatively low. The method provides a good bulk sample and is often used to verify drilling results by sinking a shaft over a drill hole. Bedrock values and characteristics can also be accurately determined when the excavations are sunk to bedrock.

Backhoe Trenches: Backhoes are a very versatile piece of equipment for sampling relatively shallow, up to about 6-m. (20-ft) deep deposits. Backhoes are mobile, fast, can dig fairly hard ground, and are inexpensive compared to hand-dug excavations. Once a trench is opened up, channel samples are taken by hand or by using the backhoe or a bulk sample can be made with all of the material from the excavation. For backhoe sampling programs, the ground must be fairly dry and stable. Care must be taken, when using a backhoe or any mechanical equipment, to keep all fuel and lubricants away from the sample material as sample contamination can result, causing the fine gold to float and thereby reducing the value of the sample.

B

ulldozer Trenches: Bulldozers are best suited to work in ground where trenches are to be dug 3 m ( 10 ft) deep or less and are in dry, stable ground. The greatest advantage of prospecting placers with a large bulldozer trench is that the trenches permit good visual inspection of the ground. Other advantages and disadvantages are similar to those associated with backhoe trenches.

Other Machine-Dug Excavations: Machine-dug excavations are shafts or pits that are dug using powered equipment such as large augers, bucket drills, or clamshell-type excavators. Digging shafts with the aid of powered equipment requires experienced operators and suitable machine access. Dry, stable ground is also needed for successful sampling operations when digging shafts and pits.

Augers: Augers for sampling placers can vary from small hand-held posthole size machines up to very large truck-mounted machines. Augers are relatively inexpensive to operate and can provide large volume samples, The disadvantages of using augers are their inability to penetrate ground with boulders, gold sorting may occur with spiral-type augers, and their inability to perform in water-saturated ground.Fig. 4.4 A sample from the upper part of the inside river gravel bar was taken to estimate gold content in upper layer of a primary terrace.

Gold Mining & Gold Prospecting Exploration Methods Prospecting Gold Gold Prospecting Methods -Photogeology Gold Prospecting Methods -Seismic Surveying Gold Prospecting Methods -Borehole Surveying Gold Prospecting Methods - Sampling for Gold Gold Prospecting Methods - Types of trenching Gold Prospecting Methods - Placer Sampling Sample Salting Processing or Washing Gold Prospecting & Record Keeping Where to Find Gold. Rivers and streams or Lakes Prospecting Quartz Reefs & Other Deposits Geochemical Prospecting Where does gold occur, where are the occurrences, where to find gold How to do Gold Panning metal detecting Gold Reserve Estimation Methods