ISO 00923:2000 pdf download

ISO 00923:2000 pdf download.Coal cleaning equipment -Performance evaluation.
6 Performance test procedures
The equipment to be tested, the feed composition, and the means of handling the feed and products, vary widely. A single International Standard to cover all cases is not applicable. The following general procedures shall be followed.
a) Samples shall be taken from the feed and from each of the products. The sampling techniques, number of increments and increment mass shall ensure that all samples taken are representative and shall comply with existing International Standards where available. Sampling of coal is covered by ISO 1988 and size analysis of coal is covered by ISO 1953.
To enable checking of results and assessment of the effects of degradation, representative samples should be
taken from all relevant streams to and from the equipment to be tested.
b) It is essential to determine the feed rate and the percentage yield to each of the products on a dry basis in accordance with ISO 1170. This should be achieved in accordance with one of the procedures given below.
Determine the mass of each product by one or more of the following methods, which are listed in order of reliability.
a) By direct weighing of the whole of each product collected over the duration of the test or through continuous weighing and integration over the duration of the test.
b) By taking regular timed increments over the duration of the test.
c) By weighing each product collected simultaneously over a selected period of the test.
NOTE 1 If it is feasible to measure both the mass of the feed (by belt weigher, weigh hopper, flowmeter, etc.) and the mass of the products, this provides a check.
NOTE 2 If the mass of one of the products cannot be obtained, it may be derived from a mass balance between the feed and other product(s).
NOTE 3 Where the solids are conveyed by a fluid, it may be more convenient to make volumetric measurements.
Representative samples should be taken from streams to determine moisture content or concentrations of solids as appropriate, so that results can be reported on a dry basis.
In circumstances that prevent the determination of yields by the above procedures, alternative procedures (e.g. ash balance) may be used.
7 Analytical procedures
The methods and procedures of size analysis and float and sink analysis shall be in accordance with ISO 1953 and ISO 7936, respectively.
The feed sample and each of the product samples should be separated into various particle size fractions depending on the degree of detail required. Because the performance of coal cleaning equipment is usually different for different size particles, the size ranges should be as prescribed in ISO 7936.
8 Expression of performance
Methods for the expression of the results of coal cleaning tests and the performance of the separation processes are given in normative annex A.
For the purpose of meeting the requirements stated in clause 1, no single method suffices by itself.
Normative annex B describes recommended methods for the calculation and tabulation of test results, and informative annex C gives graphical presentations.
NOTE 1 M-curves and washability curves describe graphically the character of the raw coal and of the products, in terms of mass and ash. Partition curves describe only the products in terms of mass and density; they can be constructed without the necessity to determine ash.
NOTE 2 M-curves have wider direct applications than washability curves, especially, for example, in three-product separations. The construction of such curves is described in ISO 7936.
NOTE 3 The écart probable (moyen) and imperfection reflect the influence of changes in the separation process rather than in the raw coal, in contrast to the formulae derived from M-curves or washability curves, which reflect changes in the raw coal as well as in the separation process.
NOTE 4 The separation density, although not a measure of efficiency, is an important characteristic of the separation and is essential to any comprehensive statement of the results of a given test.
NOTE 5 The misplaced material and the total of correctly placed material at the separation density, the ash error, the yield error, the organic efficiency and the error area can all be used for guarantee tests and occasional control tests to give an indication of the accuracy of a given separation on a given coal, and hence of economic efficiency; but they are of little value in the prediction of probable results of cleaning a range of coals by one specific process.
NOTE 6 Partition coefficients. écart probable (moyen) and imperfection are valuable for the purpose of prediction but do not give an adequate indication of the accuracy of a given separating operation on a particular coal.