Project Synopsis

Fast-track process design a sodium hydrosulfide (NaHS) production unit within an antimony refining facility.

Project Summary


The client, an engineering consulting firm, was contracted to design an antimony refining plant and subcontracted Process Engineering Associates, LLC (PROCESS) to perform a fast-track process design for the sodium hydrosulfide (NaHS) production unit of the facility.  The primary product of this project was a purchased equipment cost estimate to be used by the client in preparing an overall antimony plant project cost estimate. Specifically, PROCESS was assigned the following project tasks:

  • Task 1 – Prepare a process design basis
  • Task 2 – Perform preliminary mass and energy balance calculations
  • Task 3 – Ascertain feasibility study level equipment purchase costs for the NaHS production unit primary unit operations
  • Task 4 – Develop preliminary data sheets for the NaHS production unit primary unit operations
  • Task 5 – Prepare equipment layout drawings (plan and elevation) for the NaHS unit.

The process design basis set the input stream physical and chemical characterizations, desired operating goals and constraints for the NaHS production unit, and NaHS product stream specifications.  Mass and energy balance calculations were prepared using a combination of commercial computer process simulation software and manual calculations and were used for the development of preliminary request for quotation packages sent to qualified equipment vendors.  The equipment purchase costs were developed based on vendor quotations and an in-house equipment cost database.  The preliminary equipment data sheets contained information relative to the NaHS unit primary unit operations (dimensions, weights, power and utility requirements, major instrumentation, primary piping connections, etc.) and were used by the client, in conjunction with the equipment purchase costs, in preparing an overall antimony refining plant project cost estimate.  Equipment layout drawings were used to evaluate the approximate space requirements associated with the unit.

The primary unit operations to be employed by this unit include:

  • NaHS continuous production reactor
  • NaHS solution evaporator
  • NaHS liquor drum flaker
  • Tail gas scrubbing tower.

Several tanks, heat exchangers, pumps, and solids transport/storage systems will also be included in the unit.

Based on the project cost estimate provided to the client, it is expected that a full design of the facility will be commissioned, and PROCESS is expected to be sub-contracted by the engineering consulting firm to perform a conceptual and detail process design of the NaHS production unit in support of the antimony refining plant design project. 

Industry Type

  • Minerals & Metals Refining

Utilized Skills

  • Conceptual process design
  • Vendor bid reviews
  • Capital cost estimate preparation
  • Equipment layout drawing preparation
  • Basic engineering design package (BEP)

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