ISO 923:2000 download free.Coal cleaning eauipment – Performance evaluation.
ISO 923 describes the principles and methods for evaluating the per1ormare of equipment used for cleaning operations. Testing and sampling procedures ate specified and methods of presenting test results are detailed. Perlormance parameters are recommended and defined and their determination is formulated, thereby alIowng theN use in evaluating, companng and predicting performance levels of cleaning operations.
ISO 923 is applicable to the following types of coal cleanrg equmen1 using relative density as the main characteristic for separation:
a) dense-meceum separators;
b) jigs:
c) other separators
2 Normahve references
The following normative documents contain provions which, through reference In this text, constitute provisions of ISO 923. For dated references, subsequent amendments to. or revisions cf. any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the posebibty of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards.
ISO 1170, Coal and coke — CakUIaIIOn of analyses to different bases.
ISO 1213-1, Solid mineral fuels — Vocabulary — Part 1: Terms relating to coafpreparation
ISO 1953, Hard coal — Stre analysis by sietog.
ISO 1988, I-lard coal — San,p*ng
ISO 5048, Ccntinuous mechanical handling equrpnlenl — Bell conveyors with carrying ders — Calculation of operating power and tensde forces,
ISO 7936, Hard coal — Determination and presentation of float and sink characteristics — General directions for apparatus and precedures.
3 Terms and definitions
For the purposes of ISO 923, the terms and definitions given in ISO 1213-1 apply.
4 Performance criteria The following criteria are used:
a) the feed rate, expressed on mass and/or volume basis;
b) reference density of separation; C) sharpness of separation; d) correctly placed and misplaced material; C) ash error and yield error; f) the degree of difficulty of separation; g) material cacteristics
The ove criteria will be influenced by test conditions, which should theretore be fully reported.
Conditions. Including feed rate, should be kept uniform, monitored and maintained within prescribed tolerance limits during a test.
Where performance test results are used for prediction, process conditions should be taken Into account.
5 Performance parameters
For the standard expression of perfOrmance of a cleaning operation, determine the criteria in clause 4 by the following parameters:
a) the feed rate, expressed on mass and/or volume basis;
Keep the feed rate as uniform as possible throughout the performance test and determine It over the duration of the test by the most accurate method avadable.
Where the feed to the equçiment is by belt conveyor, determine the feed rate in accordance with ISO 5048
b) the reference density of separation, preferably expressed as both parlition density and equal-errors out-point (density);
c) the sharpness of separation expressed in terms of probable error and imperfection:
d) the distribution of correctly placed and incorrectly placed material in each product, presented graphically with respect to relative density, and the particular value of misplaced material in each product, determined at the reference density of separation;
e) the ash error expressed as the difference between the actual ash in the cleaned coal and the theoretical ash at the actual yield value;
f) the yield error expressed as the difference between the actual yield and the theoretical yield at the actual clean-coal ash value;
g) the degree of diuliculty of separation expressed In terms of near-density material (and by other relevant characteristics).
6 Performance test procedures
The equipment to be tested, the feed compoemon, and the means of handling me teed 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 teed and from each of the products. The sampling techniques, number of Increments and increment mass shall ensure mat all samples taken are representative and shall comply with existing lnlernational Standards where avaabIe. Sampling of coal covered by ISO 1968 and size analysis of coal Is covered by ISO 1953.
To enai,le checking of results and assessment of the eflects of degradation, representative samples should be
taken tram all relevant streams to and from the equment 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 Wi accordance with ISO 1170. This should be achieved in a000rdance 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 dWecl we.ghing of the whole of each product collected over the duration of the test or throui continuous we.ghing 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 I lilt is feasible to measure both the mass of the teed (by belt weigher. weigh hopper, flowmeLer, sic,) and the mass of the produc. 5*5 provIdes a ched.
NOTE 2 lIthe rrwes of one of the proc5icls cannot be obtained, II may be derived from a mass balance betwe5n the teed and other podtt4s).
NOTE 3 Where the sobds are convayed by a fluid. It may be more convenient to mie 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 defemunation 01 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 shal 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 requwed Because the performance of coal cleaning equipment is usually different for different size particles, the size ranges should be as prescrbed In ISO 7936.
8 Expression of performance
Methods br the expression of the results of coal cleaning tests arid the performance of the separation processes are given ii normative annex A.
For the purpose of meeting the requirements stated In clause 1 • no single method suffices by Itselt
Normative annex B describes recommended methods far the calculation and tabufalion of test results, and iitormative annex C gives graphical presentations.