BS ISO 23873:2010 pdf free download Hard coal — Method for the measurement of the swelling of hard coal using a dilatometer
1 Scope
This International Standard describes a method for the measurement of the swelling of hard coal using adilatometer.
2Normative references
The following referenced documents are indispensable for the application of this document.For datedreferences,only the edition cited applies. For undated references,,the latest edition of the referenceddocument (including any amendments) applies.
ISO 1213-2,Solid mineral fuels —Vocabulary —Part 2:Terms relating to sampling, testing and analysisIS0 13909-4, Hard coal and coke — Mechanical sampling —Part 4:Coal —Preparation of test samples
3 Terms and definitions
For the purposes of this document, the terms and definitions given in lSO 1213-2 and the following apply.3.1
softening temperature temperatureof initial contraction
temperature at which the downward movement of the dilatometer piston is 0,5 mmNOTESee temperature 01 in Figure 3.
3.2
temperature of maximum contraction
temperature at which the dilatometer piston reaches its lowest pointNOTESee temperature 02 in Figure 3.
3.3
temperature of maximum dilatation
temperature at which the dilatometer piston reaches its highest point
NOTESee temperature 03 in Figure 3.
3.4
maximum contraction
maximum downward movement of the dilatometer piston, measured from the zero point
NOTE 1 Maximum contraction is expressed as a percentage of the initial test-piece length.NOTE2See c in Figures 3 and 4.
3.5
maximum dilatation
maximum upward movement of the dilatometer piston after contraction, measured from the zero point
NOTE1 Maximum dilatation is expressed as a percentage of the initial test-piece length.
NOTE2See d in Figures 3 and 4.The value can be either positive or negative.
3.6
repeatability
maximum acceptable difference between two determinations which are carried out in the same laboratory, bythe same operator with the same apparatus,on test pieces prepared from the same test sample and testedsimultaneously in two different retorts during the same heating cycle or separately in the same retort duringdifferent heating cycles
3.7
reproducibility
maximum acceptable difference between the means of two determinations which are carried out in each oftwo laboratories, on representative portions taken from the same gross sample, after the last stage of samplepreparation
4Principle
A test piece, in the form of a pencil, prepared from powdered coal is heated at a constant rate in a steel retortpositioned in a furnace,the temperature monitoring system having been previously calibrated using tworeference metals of known melting points. The change in level of a piston resting upon the test piece isobserved continuously, and a record is produced which is charateristic of the swelling properties of the coal.
5Materials
The following materials are required for temperature calibration (7.1).
5.1 Graphite pencils,30 mm long, base diameter 7,4 mm, top diameter 6,8 mm, with a small cylindricalreservoir drilled in the narrow end of each pencil.
5.2Metal balls, of the following reference metals:
a) lead, of analytical reagent grade, assay(Pb) 99,98 % minimum, melting point 327,0°C;
b)zinc, assay (zn) 99,87 % minimum, melting point 419,3°℃.
5.3Water-based blacking.
6 Apparatus
6.1 Mould and accessories
6.1.1 Mould (see Figure 1), made from steel, case-hardened after machining. The bore shall be polishedafter hardening and the bore and uniformity of taper (i.e 1 in 50) shall conform to the dimensions given inTable 1.
6.1.2 Mallet, plastics head, mass about 200 g.
6.1.4 Press (see Figure 1).
6.1.5 Load cell (see Figure 1), capable of registering a load of 0 to 15 kN.
6.1.6 Pencil gauge (see Figure 1).
6.2 Dilatometer
A general arrangement of suitable dilatometer apparatus giving critical dimensions is shown in Figure 2.
6.3 Dilatometer furnace
A furnace capable of heating two or more retorts (6.6) to a temperature of 550 °C at a rate of 3 °C/min is used.
A suitable furnace (for heating three retorts) is illustrated in Figure 2 and consists of a casing fitted with a base and a top cover. The cover supports a cylindrical block of copper-aluminium alloy CA 104, of 65 mm diameter and 460 mm long. The block has three holes of 380 mm minimum depth and 15,0 mm ± 0,1 mm diameter, drilled as shown in Figure 2. The top surface may be insulated by an appropriately shaped piece of board. The block is heated electrically by an insulated resistance winding, capable of raising the temperature of the block to 550 °C at a rate of 3°C/min. The space between the block and the casing is filled with a thermal insulating material. A suitable temperature sensor is positioned in the third retort in such a way that the sensor tip lies centrally 30 mm above the internal base of the retort. The distance of 30 mm is established by using a graphite pencil (5.1) as a means of measurement.