BS ISO 12742:2020 Copper, lead and zinc sulfide concentrates一 Determination of transportable moisture limits一 Flow-table method.
6.3 Sample preparation
Homogenize the laboratory sample as quickly as possible to prevent moisture losses. Take nine test samples as follows:
a) Sample 1
Take not less than 2 kg from the laboratory sample. This sample is to be used for determining the moisture content of the sample as received. Place this sample on a drying tray or pan.
b) Sample 2
Take approximately 1,2 kg from the laboratory sample. This sample is to be used for the preliminary TML test. Store this sample in an appropriately labelled airtight container.
c) Samples 3 to 6
Take four samples of approximately 1,2 kg from the laboratory sample. These samples are to be used for the main TML test. Store these samples in appropriately labelled airtight containers.
d) Samples 7 to 9
Take three samples of approximately 1,2 kg from the laboratory sample. These samples are to be used for confirmation of TML by the graphical method. Store these samples in appropriately labelled airtight containers.
Copper, lead and zinc concentrates can undergo rapid changes in moisture when exposed to air, so all stages of the test should be accomplished in the shortest time period and shall be completed within the day of commencement. Where possible, sample containers should be covered with plastic film or any other suitable airtight cover.
The moisture result from sample 1 provides information about how far the material under test is from the flow moisture point.
As more accurate results are obtained when the moisture of the test portion is close to the flow moisture point, a preliminary test is carried out (sample 2). The result of this test is used to adjust the moisture of the final test portion to 1 % to 2 % relative below (samples 3 and 4) and above (samples 5 and 6) the flow moisture point.
To check the main flow moisture point graphically, three more samples (samples 7 to 9), having moisture values higher than the flow moisture point, are tested. The flow moisture point is the extrapolation to zero of the least squares linear regression of the test portions showing a measurable displacement. The value obtained this way will be used to validate the main flow moisture point.
7.2 Preparation of test portions3)
Sample 1 shall be prepared in accordance with ISO 10251. Proceed to 7,7.BS ISO 12742 pdf download.