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Sodium Hydrosulfide (NaSH)-An Alternative to Sulfur Production

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Sodium Hydrosulfide (NaSH)
Structure of a NaSH Crystal

Introduction

Sodium Hydrosulfide (NaSH) solution is an alternative product to sulfur from hydrogen sulfide.

Much hydrogen sulfide ends up on solid bed medias such as iron sponge or Sulfatreat®. This is disposed of in landfills. These processes are justified in most cases.

Depending on your production rate of hydrogen sulfide, a Claus Unit may be just what you need. However, there are certain cases where the intermediate volumes of gas can justify a Sodium hydrosulfide (NaSH) unit.

Typical Processes that Consume NaSH

When the markets exist in your geographical region consider on onsite sodium hydrosulfide (NaSH) production unit.

Sodium hydrosulfide (NaSH) is a chemical reagent with numerous applications within predominately three (3) industries:

  1. Kraft Paper Milling. In Kraft, pulping sulfidity is controlled through the use of reduction furnaces which reduce sodium sulfate plus caustic soda to sodium sulfide. Planned or unplanned, outages result in reduced concentrations of sulfidity. Sulfidity is measured with an ORP (Oxidation reduction Probe). NaSH is typically introduced during these outages to return sulfidity levels to pre outage levels. Additionally, Kraft mills that are located near (freight) a waste NaSH production site control sulfidity with only purchased NaSH plus purchased NaOH. These opportunities are typically located in the SE portions of the United States as oil refineries present economics that offer incentive to pursue Kraft pulping without the use of reduction furnaces. Often times these waste NaSH facilities contain Sodium carbonate as the H2S source which also has a high concentration of CO2.
  2. Copper Sulfide Flotation. In the Copper mines that predominate the western mountain ranges of North and South America exist most of the world’s copper. Additionally, as these mines also contain economically viable Molybdenum, a moly circuit is also employed. The process feeds the Cu Sulfide concentrate produced through flotation and applies a reverse flotation circuit to separate the Moly sulfide from Copper sulfides. In this case, the MoS floats and the CuS is depressed in a bank of flotation cells. The control devise is also an ORP meter typically controlled at between -450 mv and -500 mv. NaSH is the reagent chosen to maintain the pulp at the desired ORP.
  3. Leather Depilatory. NaSH solutions are applied in a process called blueing to remove hair from cow, calf, sheep or any other animal hide.

R.C. Costello & Assoc., Inc. provides Engineering Design and construction of NaSH plants.

Phone: 310-792-5870 Email: rcca@rccostello.com

Website: rccostello.com