GB/T 2007.2-1987 English PDF (GBT2007.2-1987)

This General Rules applies to the preparation of samples taken according to the method specified in GB 2007.1. The prepared sample shall be representative of the quality characteristics of the original sample and suitable for analysis or test requirements.

GB 2007.2-1987
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
UDC 622-3:543.05
GB 2007.2-87
Replacing GB 2007-80
General rules for the sampling and sample
preparation of minerals in bulk
Sample preparation by manual method
APPROVED ON: DECEMBER 15, 1987
IMPLEMENTED ON: OCTOBER 1, 1988
National Standard Bureau
Table of Contents
1 Scope of application ... 3
2 Reference standards ... 3
3 Terms and definitions ... 4
4 Sample-preparation tools ... 4
5 General requirements for sample preparation ... 5
6 Crushing of the sample ... 6
7 Mixing of the sample ... 6
8 Reduction of the sample ... 6
9 Precision of sample preparation ... 10
10 Check of sample preparation system error ... 11
11 Sample preparation procedure example -- Riffle reduction method ... 12 12 Sample containers and labels ... 13
Annex A Mechanical mixers, reducers (Reference) ... 14
Additional information: ... 18
General rules for the sampling and sample
preparation of minerals in bulk
Sample preparation by manual method
1 Scope of application
This General Rules applies to the preparation of samples taken according to the method specified in GB 2007.1.
The prepared sample shall be representative of the quality characteristics of the original sample and suitable for analysis or test requirements.
This method describes the preparation of the following samples:
a. Moisture sample: particle size - 22.4 mm, 5 kg; - 10 mm, 2.5 kg.
b. Component analysis sample: maximum particle size 180 μm (80 mesh)
250 g;
c. Particle size sample: the sample is naturally air dried to make a particle size sample.
2 Reference standards
GB 2007.1 General rules for the sampling and sample preparation of minerals in bulk - Sampling by manual method
GB 2007.3 General rules for the sampling and sample preparation of minerals in bulk - Experimental method for evaluation of quality variation
GB 2007.4 General rules for the sampling and sample preparation of minerals in bulk - Experimental methods for checking the precision
GB 2007.5 General rules for the sampling and sample preparation of minerals in bulk - Experimental method for checking the bias of sampling
GB 2007.6 General rules for the sampling and sample preparation of minerals in bulk - Determination of moisture content - Heat drying method
GB 2007.7 General rules for the sampling and sample preparation of minerals in bulk - The method for determination of size by manual sieving
I. Sample reduction sieve; 22.4 mm × 22.4 mm, 10 mm × 10 mm, 1 mm × 1
mm, 180 μm sieve.
5 General requirements for sample preparation
5.1 Sample preparation principle: The sample preparation is carried out in the following three operation sequences (pre-drying if necessary).
Crushing: Reduce the particle size of the sample by crushing or grinding. Mixing: Make the sample even.
Reduction: The sample is divided into two or more portions to reduce the mass of the sample.
The above three operations are performed once to form a stage of sample preparation. The stage of sample preparation shall select the sample amount that reduces the sample preparation error without retaining too much sample, and the sample preparation error is roughly inversely proportional to the sample amount retained at each stage. In order to reduce the sample preparation error, it is required to reduce the sample preparation stage. If the sample preparation stage is increased, the sample preparation error will also increase accordingly, unless the sample amount retained per stage is increased.
5.2 During the sample preparation process, the composition of the sample shall be prevented from changing and contaminating. Moisture samples shall be protected from moisture changes.
5.3 Pre-drying of sample: When the sample is too wet and too viscous to be sieved, crushed and reduced, it can be dried at a temperature lower than the temperature that may cause quality change (air drying or drying oven drying), until the sample can pass freely through the crusher and reducer. Pre-drying can be carried out at any stage of the sample preparation (see GB 2007.6-87 for the method for determining pre-drying moisture).
5.4 In case of large batch size, long loading and unloading time, rain, high temperature and other conditions, the duplicate sample shall be made into the moisture sample for measurement. If the sample cannot be prepared
immediately, the moisture sample shall be placed in a sealed container to prevent changes.
5.5 The reduction and reuse of particle size samples, moisture samples, and component analysis samples shall be specified in various standards for
sampling and sample preparation of ores.
6 Crushing of the sample
Mechanical equipment shall be used for the crushing of the sample. Manual crushing is limited to crushing individual bulk samples into the maximum feed size of the crusher at the first stage.
It shall select suitable crusher and grinder according to the hardness, particle size of the ore and the use of the sample (for the crushing of the moisture sample, it should not use non-sealed crushers that are easily generate heat or have large air flow).
The performance of the crusher shall be checked regularly and adjusted to a discharge particle size smaller than the specified particle size (checked with the sample reduction sieve). In the process of preparing the component analysis sample, the portion which is difficult to be crushed tends to have a difference in component, so it is necessary to crush all the sample to the specified particle size.
Use this batch of ore (no sample) to pass through the crusher before sample preparation and then clean it. Samples remaining inside the crusher after sample preparation must be taken out to prevent loss. In sample preparation, the crusher shall be uniformly fed to avoid filling the crusher, so as to change the running speed of the crusher and the particle size distribution of the discharge.
7 Mixing of the sample
MIX the sample by any of the following methods:
7.1 Manual mixing
a. The sample is continuously passed through the riffle for three times, and the two portions of sample are combined after each pass.
b. Small particle size samples (< 1 mm) can be mixed by hand three times. 7.2 Mechanical mixing
After the sample has been crushed to less than 10 mm, it can be mixed using a double-cone mixer or a V-shaped mixer (see Annex A).
8 Reduction of the sample
The reduction of the sample can be either by mechanical or manual methods. (The width of the opening of the hopper and
chute is more than three times the maximum particle size)
The riffle (see Figure 1) is a non-mechanical sample reducer. The sample is divided into two equal portions. The adjacent grids discharge to the opposite receiving container. The sample is usually fed by hand.
The width of the grid is at least 2.5 times the maximum particle size of the sample, and half of the quantity of the grids is generally more than 8. The riffle used shall be checked according to GB 2007.4 and GB 2007.5, and it can be used only if it meets the requirements.
Reduction procedure:
a. The sample is mixed three times through the riffle and placed in a feed container.
b. Flatten the sample in the feed container, and make the sample evenly spread along the entire grid of the riffle when reducing. The feed rate shall be controlled to ensure that the grid is not blocked. If the riffle is found to be blocked by the sample, it must be cleaned before continuing to operate. c. The sample that passes through the riffle is collected in two receiving containers.
d. Randomly select the sample in a receiving container as the reserve
sample. If further reduction is required, the reserve sample may be passed through the riffle again or more times. At this time, the reserve sample is alternately collected from the receiving containers on both sides of the riffle. The receiving containers shall be in close contact with the body to reduce dust and moisture loss.
e. Reduction retention-amount
When preparing the component analysis sample by reducing a large
sample or a duplicate sample, the minimum sample retention-amount
corresponding to the maximum particle size cannot be less than that
specified in Table 1, otherwise it cannot be reduced at this stage.
When the reduced increment forms a duplicate sample or a large sample, and the coefficient of variation CV of the increment amount is > 20 %, the riffle reduction method cannot be used.
8.2.2 Increment reduction method
This method is a quantitative reduction method with large reduction ratio and high precision. It is also a method by which the moisture sample can be taken