GB/T 2009-1987Method of sampling and sample preparation of bauxite in bulk (English PDF)

5.1 Brief sampling procedure

5.1.1 Verify the delivery batch or sampling unit to be sampled and its mass.

5.1.2 Determine the intended use of the sample and the quality characteristics to be tested.

5.1.3 Determine the increment mass and the capacity of sampling tools based on the maximum particle size of the ore.

5.1.4 Determine the type of quality variation of the delivery batch and the number of increments required to achieve the specified sampling precision.

5.1.5 When using systematic or stratified sampling methods, determine the minimum number of increments to be taken from the delivery batch; when using a secondary sampling method, first select the number of trucks to be sampled from the entire delivery batch; then take increments from the selected trucks.

5.1.6 Determine the sampling interval; take increments at fixed mass intervals or time intervals.

5.1.7 Determine the sampling locations and the method for taking increments.

5.1.8 Determine the method for combining increments to form sub-samples or master samples as required.

5.2 Sampling tools

Pointed steel shovel; b. Sampling scoop (see Table 3 and Figure 1); a sampling batch, unit, or layer. The SW value is determined in accordance with GB 2007.3.

When the type of quality variation is unclear, a verification test shall be conducted as soon as possible; or integrated into routine sampling operations to determine the variation type. For bauxite with unknown quality variation types or material requiring particle size analysis, the number of increments shall be selected based on the criteria for large quality variation.

5.4 Increment mass

The minimum mass for each increment is determined based on the maximum particle size (see Table 3). The mass of each collected increment shall be approximately equal, with a coefficient of variation (CV) not exceeding 20%.

When the increment mass' CV >20%, samples shall be prepared and analyzed individually; or combined into sub-samples or bulk samples only at an appropriate stage of sample preparation where the masses of the divided increments are approximately equal.

5.5 Sampling methods

5.5.1 Systematic sampling method

Increments are collected at fixed mass or time intervals during the loading, unloading, processing, or weighing of a batch of bauxite in bulk. The interval between increments can be calculated using Formula (3), based on the number of increments specified in Table 1 and the actual batch size. Where. T - mass interval of sampling, in t;

Q - batch size, in t; n - number of increments specified in Table 1; T' - time interval of sampling, in min; G - loading/unloading rate per hour, in t/h.

The first increment may be selected randomly within the first interval, but not at the very beginning of that interval; subsequent increments must be taken at the calculated interval, and the actual sampling interval must not exceed the calculated one. If the required number of increments based on the fixed interval has been collected but the loading, unloading, processing, or weighing of the bauxite is still ongoing, sampling must continue at the original interval until the entire batch has been moved.

When sampling from a conveyor belt or a discharge point, the full cross-section of the bauxite stream must be intercepted. When sampling during loading, unloading, or stockpiling operations involving grabs, lifting slings, loaders, or other equipment, samples shall be taken from newly exposed surfaces or directly from the handling equipment. Sampling points shall be evenly distributed throughout the entire batch of bauxite, rather than being limited to the surface or a specific localized area. The diameter of the sampling point shall be at least three times the maximum particle size, but no less than 100 mm.

The particle size distribution of the collected increments shall roughly correspond to the particle size distribution at the sampling interval or location; the particle size distribution of the resulting bulk sample shall roughly match that of the entire batch of bauxite.

5.5.2 Stratified sampling method

For a batch of bauxite in bulk undergoing loading, unloading, processing, or stockpiling, samples are taken from multiple layers (at least three layers). Sampling points are distributed evenly across newly exposed surfaces, with the number of increments determined proportionally based on the mass of each layer. Attention must be paid to particle size distribution to ensure that the particle size distribution of the increments from each layer matches the particle size distribution of the bauxite in that layer (sampling point ranges are the same as in 5.5.1). The number of increments to be taken from each layer is calculated using Formula (4).

Where. n1 - the number of increments taken from each layer; n - the number of increments specified in Table 1; QL - mass per layer, in t; Q - batch size, in t.

5.5.3 Truck sampling method

In principle, increments shall be collected from randomly selected points on surfaces newly exposed during the loading or unloading of trucks, or from the stream of ores during unloading. […]

5.5.3.1 Sampling method for all trucks