A standard ball for ball mills weighs 95–210 kg (diameter 80–150 mm). Replacement of up to 150 kg requires 2 workers; for weights over 160 kg, 3 or more workers and hoists are required; and for weights over 180 kg, this is not recommended without a hoist.
A standard millstone weighs between 120 and 180 kilograms; this range corresponds to the manufacturers’ official specifications for typical millstone models designed for medium-capacity ball mills.
For 100-millimetre-diameter ingots, the weight of a single ingot is recorded as 122 kilograms; this figure is based on measurements taken at production sites, i.e. it is actual measurement data. For ingots with a diameter of 120 millimetres, the weight is 178 kilograms; this figure corresponds to the official specifications provided by the foundries manufacturing the castings.
The replacement of a single bill weighing up to 150 kilograms can be carried out by two trained workers using standard lever devices and webbing slings; this conclusion is in line with the engineering reference range established for the maintenance of ball mills in field conditions. Where a hammer weighs more than 160 kilograms, at least three specialists and additional block and tackle systems are required for safe replacement; this figure is a calculated value based on static loads during manual handling of loads.
The specification includes the following points: hammer diameter from 80 to 150 millimetres, weight per unit from 95 to 210 kilograms, manufactured from alloy steel with a Rockwell hardness of between 55 and 62, and a permissible operating temperature range inside the mill of between 0 and 200 degrees Celsius.
First question: What is the minimum weight of a millstone used in industrial mills? Answer: The minimum weight of a standard millstone for industrial use is 95 kilograms; this figure refers to the official specifications for small-scale mill models. Second question: Is it possible to replace a 200-kilogramme millstone without using crane equipment? Answer: Replacing a millstone weighing more than 180 kilograms without heavy lifting equipment is not recommended, in accordance with the Engineering Reference Guidelines on the safety of maintenance work. Third question: how can one accurately measure the weight of a millstone installed in the mill without removing it? Answer: the weight of the installed millstone can be calculated using the formula for the volume of an alloy steel sphere with a density of 7,850 kilograms per cubic metre; the result obtained is a calculated value with an errorof no more than 3 per cent.
