Rapid preparation of robust pressed powder briquettes containing a styrene and wax mixture as binder

The binder is composed of nine parts (by mass) styrene copolymer and one part wax. Both ingredients are marketed under brand names and are available as 10 μm powders, which can be conveniently blended in bulk. Exceptionally robust briquettes containing 10% binder have been made from a great variety of sample types, including metal powders, ion exchange resins, coal, charcoal, graphite, ash, vegetable matter and geological materials. Normally the sample and binder are milled together in a swing mill and milling behaviour is not adversely affected. The briquettes are not affected by vacuum, radiation or age. Erratic milling efficiency of the six‐vessel swing mills used and modifications to overcome the problem are described. For the most satisfactory ejection of a briquette, the cylinder wall of the die should taper slightly outwards near the ejecting end. A pressure of at least 0.04 MPa is recommended to ensure maximum x‐ray fluorescence intensity, but higher pressures improve briquette strength. In the above‐mentioned laboratory 0.23 MPa is normally used. The time the briquette is held under full load is not important. The simplicity of the method makes it possible to mill and press more than 1000 briquettes per day. Binder cost is approximately 3 cents per gram.