Solids transfer method

A method of introducing finely divided coal into a circulating liquid pressure system where the finely divided coal is retained at atmospheric pressure and the system is under a pressure of at least 10 atmospheres, comprising the steps of introducing a Venturi tube, said tube having a throat of predetermined cross-section in the liquid system, pressurizing the system with a liquid flow so as to generate a negative pressure in the Venturi tube, providing an inlet port at the Venturi throat, introducing finely divided coal into the throat through said port so that negative pressure at the throat operates to siphon finely divided coal into the system, wherein the liquid is a dense liquid having a density greater than the density of coal and immissible relative to the coal maintaining the system at a temperature sufficiently high to keep said dense liquid in a liquid state, transporting the coal and dense liquid to a separation chamber, separating the coal from the dense liquid while in said separation chamber by flotation, sweeping the coal from the separation chamber by a gaseous fluid into a reactor and recirculating said dense liquid.