Abstract
Flashing slurry flow is common to autoclave (AC) processing of refractory ore and leads to substantial AC process facility losses each year. Despite its detrimental effect, this phenomenon is comprehended by relatively few in the global slurry mining industry. While esoteric, flashing is central to the operation, sizing, and health of the AC system. Correct understanding of multiphase flow dynamics impacts important aspects of the AC process, such as AC letdown equipment wear (including the level control valve), AC throughput, and level control. The first section of this paper serves as an introduction to the first-principle bases for flashing multiphase flow. It covers both the thermo- and flow dynamics of AC letdown applications. The fascinating characteristics of this science provide helpful insights into avoiding costly problems, troubleshooting operation issues, and innovating novel AC letdown solutions.
The second section of this paper describes a novel sizing technique for AC level control valves (LCV). This technique uses specific adaptations of thermodynamics and compressible flow science applied to three-phase flow. It goes beyond basic sizing techniques currently common in industry by including ceramic material properties, thermoelasticity, AC level control, statistical control of temperature and pressure, health monitoring, and AC starts and stops. By understanding and accurately applying these disciplines, some of the negative effect of flashing flow on LCVs can be prevented.