Assay Sampling Protocols for Industrial Metal Scrap Valuation
Assay sampling protocols establish true dry weight and payable metal content, directly governing settlement values, working capital allocations, and lender borrowing base limits.
Bone Dry Factor
Meaning
Moisture correction coefficients represent the mathematical multipliers used to convert wet weight to dry weight in bulk commodity trading. The bone dry factor is determined by heating a sample until it reaches a stable weight. This ratio is expressed as a decimal where a value of one represents a completely moisture-free material.
Moisture Measurement
Laboratory technicians heat a wet sample at a set temperature of one hundred and five degrees Celsius for several hours. This drying process continues until successive weighings show no further change in mass, indicating all surface water has evaporated. High precision balances measure the weight before and after heating to prevent errors.
This ensures that the moisture content is calculated down to the decimal point and prevents disputes between the seller and the buyer over moisture loss.
Dry Calculation
Multiplying the wet tonnage of a concentrate shipment by the bone dry factor yields the dry weight of the material. This dry weight forms the basis for metal content calculations and commercial payments. If the cargo holds high moisture, the dry weight will be lower than the shipped weight.
This prevents buyers from paying for water.
Bulk Valuation
Contracts specify the penalty limits for excess moisture in concentrates. Since shipping companies charge for the total wet weight, knowing the bone dry factor is necessary to evaluate the transport costs and the value of the dry metal. High transport costs for water can ruin the margins of a shipment.