BS ISO 18843:2015 pdf download – Aluminium oxide primarily used for the production of aluminium — Method for the determination of flow time

02-21-2022 comment

BS ISO 18843:2015 pdf download – Aluminium oxide primarily used for the production of aluminium — Method for the determination of flow time.
1 Scope This International Standard sets out a method for determining the amount of time taken for a given quantity of smelter-grade alumina to flow by gravity through a precisely constructed standard funnel. NOTE Variations in the apparatus and other test variables can create significant inter-laboratory differences in results. (See Table A.1.) 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. AS 4538.2, Guide to the sampling of alumina — Part 2: Preparation of samples 3 Principle The standard funnel is loaded with a specified mass of alumina. The time for the alumina to flow out of the funnel is determined. 4 Apparatus 4.1 General The test may be carried out using manual or automatic timing. An automatic device is shown in Figure 1. 4.2 Funnel, precisely constructed of a corrosion resistant metal, e.g. brass or aluminium, as shown in Figure 2 with an abrasion resistant material, e.g. hardened stainless steel, insert with an outlet diameter of (3,95 to 4,00) mm; this diameter is critical. 4.3 Stand, a suitable device for supporting the funnel. 4.4 Timing device, either a stop watch or automated device capable of an accuracy of 1 s. 4.5 Top-loading balance, capable of weighing 100 g to the nearest 0,1 g. 4.6 Sieve, with apertures within the range (300 to 400) µm to remove abnormal oversize material. 4.7 Container, suitable for containing the test sample. 4.8 Sealable container, suitable for containing and storing the funnel.
6 Procedure 6.1 General This procedure is for manually timed determinations. 6.2 Number of determinations Three determinations shall be carried out. 6.3 Determination Each determination shall be carried out as follows. a) Ensure the funnel is clean with no surface oxides present and dry prior to use; otherwise flow times will not be reproducible. Frequent use has usually been found to be an adequate cleaning method. b) Set up the apparatus by placing the funnel (4.2) on the stand (4.3) in a vibration-free environment. c) Ensure that the funnel is secure on the stand and that the upper surface is precisely level. d) For apparatus not in frequent use, clean the funnel by passing several portions of alumina through it [see a)]. Discard this material prior to testing. e) Take one of the prepared samples (see Clause 5) and accurately weigh a test portion of (100 ± 0,1) g and place into the container (4.7). (See Clause 5.) f) Pour the test portion uniformly into the funnel while manually obstructing the outlet. g) Start the flow by removing the outlet obstruction and immediately commence timing. Stop the timing as soon as all the sample has passed through the funnel. Never tap the funnel. h) Repeat the procedure with the other two test portions (Clause 5). i) Remove the funnel from the stand and wipe the funnel clean with a dry cloth. Replace it in the sealable container (4.8) to prevent damage to the outlet orifice and minimize atmospheric oxidation of the inner surface.

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