Process for the upgrading of coal

In a process for upgrading relatively fine coal particles which are suspended in an aqueous liquid by treating such a suspension as an aqueous slurry of feed solids and mixing it with an oil-phase binder, agitating the resultant slurry to agglomerate coal particles, and then separating the agglomerated particles from the slurry, the improvement for increasing the cost-effectiveness of the coal particle agglomerating and separating process by using a ratio of binder to feed solids which substantially minimizes both the proportion of the residual non-agglomerated solids which remain within the slurry after the agglomerated particles have been separated from the slurry and the ratio of binder to feed solids, comprising:

• mixing and agglomerating measured amounts of feed solid particles and binder;
• removing the agglomerated particles and measuring the proportion of the feed solid particles which were not agglomerated and not removed;
• repeating said agglomerating and measuring steps while using a different ratio of binder-to-feed solid particles and measuring the resultant proportion of feed solid particles not agglomerated and not removed;
• and
• using a ratio of binder-to-feed solid particles having a value such that an incremental increase in the ratio causes only a relatively small decrease in the proportion of feed solid particles which are not agglomerated, since the ratio used has a value corresponding to a substantially asymptotic portion of a curve of the variation in proportion of non-agglomerated feed solid particles with increase in the ratio of binder-to-feed solid particles.