Desalination Plant - Brine Refining and Salt Production

Industry: Metals & Mining


INTRODUCTION

Since 1994 when there was a partial collapse at a salt mine in Cuylerville, NY, highly concentrated brine (saltwater) was being squeezed upward. The problem to solve was to stop the rising elevation of concentrated salt solution that would eventually endanger nearby aquifers. The level of brine rose at a very predictable rate approximately 60 gallons per minute (about 17 tankers per day). The brine must be pumped down continuously at the same rate in order to protect the aquifer.

SOLUTION

Since pumping and trucking away 17 tankers a day to a disposal site was not practical, the approved scheme was to build a crystallizer plant. This plant refines the brine and produces salt and clean water. Optimation provided material handling, process engineering, controls and automation services for the crystallizer plant and process. The heart of the process is a Three-Effect Crystallizer with each effect (or stage) cascaded to improve energy efficiency. The first effect uses steam from a boiler as a heat source. Steam that is flashed off in the first effect is then used as a heat source for the second effect; similarly steam flashed from the second effect is used as a heat source in the third stage. Each stage boils the brine under vacuum to increase its concentration. The saturated brine with suspended solids is fed to a device called a hydroclone and thickener to separate much of the clear liquid (or centrate). Next a centrifuge, acting similarly to the barrel of a clothes dryer, spins the solution, forcing water centrifugally out of its drum and leaving behind the cake on a pusher arm. When the system is at steady state, a dry cake (about 3% moisture) travels from a centrifuge into a pair of rollers that form briquettes. These briquettes are ready to be used in water softeners. If the distillate (distilled water) from the process is post-treated, it can then be used for drinking water.

RESULTS

This fast-track project had some unique challenges. The project required the desalination of highly saturated brine, and was located in a flood plain requiring attention to structural design and equipment selection to meet special codes and regulations. Agreements are in place that no profit is to be generated; the emphasis is on environmental results. This project provides a basis for a long-range solution to a serious environmental challenge. The team has assumed that this condition will need to be managed for over 400 years.

It is likely that the technology and processes implemented will be studied to provide lessons to help areas of the globe with limited fresh water.

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  • Metals & Mining

  • Process / Mechanical Engineering
  • Process Control
  • Systems Integration

  • Continuous Control
  • Material Handling
  • Process Monitoring
  • Project Coordination

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