What is ISO 20904 about?
ISO 20904 is an international standard on hard coal that discusses the procedures to create samples for test. ISO 20904 sets out the basic methods for sampling fine coal, coal rejects or tailings of nominal top size <4 mm that is mixed with water to form a slurry. At very high ratios of fine solids to water when the material assumes a soft plastic form, the mixture is correctly termed a paste. The sampling of pastes is not covered in ISO 20904.
The procedures described in ISO 20904 primarily apply to the sampling of coal that is transported in moving streams as a slurry. These streams can fall freely or be confined in pipes, launders, chutes, spirals or similar channels. A sampling of slurries in stationary situations, such as a settled or even a well-stirred slurry in a tank, holding vessel or dam, is not recommended and is not covered in ISO 20904.
ISO 20904 describes procedures that are designed to provide samples representative of the slurry solids and particle size distribution of the slurry under examination. After draining the slurry sample of fluid and measuring the fluid volume, damp samples of the contained solids in the slurry are available for drying (if required) and measurement of one or more characteristics in an unbiased manner and with a known degree of precision. The characteristics are measured by chemical analysis or physical testing or both.
The sampling methods described applying to slurries that require an inspection to verify compliance with product specifications, determination of the value of a character as a basis for a settlement between trading partners or estimation of a set of average characteristics and variances that describes a system or procedure.
Who is ISO 20904 for?
ISO 20904 on Hard coal-Sampling of slurries is beneficial for
- Producers of coal
- Coal laboratories
Why should you use ISO 20904?
A sampling of coal is a method of extraction of a quantity of coal from a larger quantity to provide material for testing and analysis so that the properties and composition of the larger quantity can be reliably estimated.
ISO 20904 provides guidance regarding the principles of sampling slurries, sampling schemes, the precision of sampling and determination of increment variance, time-basis sampling, mechanical sampling from moving streams, manual sampling from moving streams, sampling of stationary slurries.
As a user of ISO 20904, you can be assured of the methods used to obtain samples of fine coal, coal rejects or tailings. The information provided by ISO 20904 on sampling helps the user in saving time, collecting data and summarising more quickly. With ISO 20904 you can determine the quality of hard coal efficiently, in this manner you’ll be in a better position to make decisions.
What’s changed since the last update?
BS ISO 20904:2020 supersedes BS ISO 20904:2006, which is withdrawn.
The changes compared to the previous edition are as follows:
- An amendment to Figure 6 b Examples of correct and incorrect designs for cross-stream slurry cutters
- Correction to Figure 7 b Sample by-line for manual sampling of slurry in a pipe