Hi Kaushlesh,

Your question about a study of stratification suggests that the objective is to sample in-situ coal seams in order to determine size analysis and float sink analysis on the basis of test portions of a mass optimized for your laboratory rig. If your study is based on samples from different strata within the same seam, it would make sense to select from each distinctly different stratum a primary sample of no less than sixteen (16) times the mass of a test portion required for the rig. Each primary increment should have a mass of 1 kg.

Each primary sample should be homogenized prior to division with a Gilson SP1 divider or by incremental division with a properly designed scoop. If your laboratory rig is designed to process test portions with a mass of 1-2 kg, the mass of a primary sample should be 15-30 kg. If you want to estimate the analytical variance of size consist and float/sink, you should select a second test portion at the highest level of division.

If each primary sample is selected at specific coordinates, then your study would generate test results that can be used to verify spatial dependence between sampled positions within the coal seam. Do not fiddle around with Gy's sampling constant. It does not even apply to homogeneous populations simply because his ubiquitous sampling constant has its own variance.

Kind regards,

Jan W Merks ■

Dear All.

Some one is familiar with coal sampling as per ASTM D7256? the ASTM D2234 is complementary with ASTM D7256 ?

ASTM D7256 Item 8.2 “Division of the gross simple before crushing”, allow to obtain a sample for each primary in base of 6 subsamples in 3 kilos each.

The number of primary cuts for batches of 5000 ton is, as per item 8.1.1.5, 35 x root (5000/1000) = 78; => quantity of mass collected per batches of 5000 ton is 78 x 6 x 3 = 1404 kilos.

For shipping of 70.000 Ton => 14 batches x 1.404 kilos samples 2” / batches = 19.656 kilos… incredble.

Some body can giveme coments about??

Many thanks. ■

We need to know which standard we are following. accordingly number of increment can be determined. Similarly how much quantity will be as primery sample is to be determined by lump size of material. Based on that cutter size shall be decided and then exact total quantity per lot can be decided.

We shall help you out as we are one of the turnkey supplier for Auto Sampling System.

Thanks

Rajesh Kumar

Merit Technologies India Ltd.

No. 152, Defence Colony, Ekkattuthangal,

Chennai -97, Tamilnadu

India

Phone: +91- 44 -22334099,22318697/98/99

Fax.: 044 - 42647382

E –Mail: rajesh@merittech.co.in

Web Site:www.meritbulkhandling.com ■

How about taking a close look at ISO Standards for mechanical and manual sampling of coal? Why not experiment with interleaved primary samples? And why not design mechanical sampling systems that routinely selects pairs of interleaved final systems samples? JanWMerks ■