Mining Ore Sampling Techniques and Procedures

Cutting speed depends on mining velocity. The cutter's speed must remain constant throughout its journey through the ore flow.

Sampling Methods

Sampling can be performed using manual or mechanical methods. Manual methods include cone and quartering, sampling with scoops or shovels, and using sampling tubes.

Manual Sampling Techniques

Cone and Quartering

1. Stack material into a conical pile by shoveling.
2. Form a cake or 'qeqe'.
3. Divide the cake into four equal fractions.
4. Take two opposite quarters as the sample; reject the other two.
5. If the sample size is adequate, combine the two retained quarters and reduce their size.
6. Repeat steps 1-4 as necessary until the desired sample size is achieved.

Sampling Scoop or Shovel

This procedure is used when ore is moved from one place to another. It involves taking a sample with a scoop or shovel every 2, 3, 4, or 5 strokes. In practice, taking the fifth or tenth stroke to form the sample is common. This method also applies to subdividing a sample to obtain an appropriate size for further analysis. A disadvantage of this method is its potential inaccuracy, as shoveling relies on the operator's technique.

Sampling Tubes or Catheters

Used for sampling concentrates. The sampling tube or probe should be long enough to cross the entire lot being sampled.

Sample Preparation

When preparing samples for chemical analysis, the following considerations are important:

The number of samples obtained is assessed. For large ore lots, a further reduction in quantity is performed using a sampling method. This reduces the sample volume and aims to achieve greater uniformity.

Mechanical Sampling Method

Riffle Splitting

The riffle method uses a cutter to divide the material into two approximately equal fractions. To select a riffle, it should be sized appropriately for the particle size of the sample being split.

Procedure

To homogenize the sample, the material should be rolled or mixed using the proper procedure for its type. The sample then passes through successive quartering steps to obtain a representative sample.