Abstract: A method is disclosed for leaching a gold ore which is refractory due to the presence of sulphide minerals of arsenic and antimony. The ground ore is leached with cyanide in a pipe reactor at a pressure of between 5 and 8 MPa. The terminal pH value of the pulp is controlled to be 10 or less than 10.

Abstract: An introduction process and apparatus is described concerning the continuous elution of a value, i.e. a metal value such as gold, from a particulate carrier by a counterflow of stripping liquid through the pressurized vessel in which the loaded particulate carrier is introduced to the vessel as a low velocity plug in a liquid carrier. The extraction process is also used with the continuous elution process in which the particulate material is extracted from the bottom part of a pressure vessel through a discharge pipe extending therefrom and in which a discharge liquid is introduced into the discharge pipe upstream of the discharge end under such pressure as to maintain a head of the discharge liquid upstream of that location and a flow of the liquid downstream from the location to transport the particulate material through the discharge pipe.

Abstract: Gold and/or silver is leached from comminuted ore with an alkaline cyanide lixiviant at a superatmospheric pressure of at least 25 bar and with high purity oxygen (at least 90% pure) to reduce the residence time at high yield.

Abstract: An improved cyanide process sprays an ore-cyanide leach solution into air at a high velocity to oxygenate the slurry and catalyze the reaction between the ore and cyanide leach solution.