Develop preliminary process design information (FEL-2) for a demonstration sized process to recover rare earth elements from a mined ore based on pilot plant data.
PROCESS DESIGN FOR A RARE ELEMENTS PRODUCTION DEMONSTRATION PLANT
The client, a mineral resource exploration and development company, contracted Process Engineering Associates, LLC (PROCESS) to perform a Front-End Loading Phase 2 (FEL-2) process design for a hydrometallurgy demonstration (demo) plant. The FEL-2 design provides information to develop a preliminary capital and operating cost estimate for the new demo plant.
The demo plant purpose is to recover rare earth elements in the form of mixed rare earth oxides using the process technologies identified by the client as being optimal for the intended operations. The client desired to operate this unit to optimize its process, demonstrate its viability, and evaluate the suitability of the various process components to the specific operating tasks. The client had completed feasibility studies and operated a pilot plant that provided information that was used as a basis for the design of this demo facility. The project included the following:
- A Heat and Material Balance (HMB) was completed using METSIM mining simulation software for the bulk of the hydrometallurgy unit operations, and CHEMCAD process simulation software was used for the operations designated to recover hydrochloric acid (HCl) using distillation combined with mechanical vapor recompression. Data extracted from the HMB that was of particular interest to the client included:
- Ore feed rate and characterization for rare earth element feed rates
- Rare earth oxalate production
- Rare earth oxide production capacity
- Reagent requirements
- Water requirements
- Tailings output
- Ammonium nitrate by-product production
- Chlorides by-product production
- Thorium and uranium balances.
- Process Flow Diagrams (PFDs) were prepared that depicted the major equipment, and equipment connectivity and arrangement. The PFD stream numbers were identified in the HMB tables so each stream was characterized by component flow rates from the METSIM and CHEMCAD models.
- Heat demands from the HMB were used to calculate utility requirements for cooling water, steam, and chilled water. Flow rates and required pressures were used to calculate power requirements for pumps and agitators.
- HMB component flows and utility rates were used to provide the following specific parameters:
- Storage capacity requirements for reagents
- Production rates of rare earth oxides and chlorides
- Waste profiles for leach tailings and distillation bottoms residues
- Number of drums required to collect solids throughout the process
- Energy Table summarizing consumptions of steam and power
- Leaching reactor and thorium removal reactor sizes
- Equipment List with Capital Cost Estimate
- Operating Cost Estimate using reagent prices and manpower estimates from previous client pilot plant information.
PROCESS compiled the above information into a report that was issued to the client that included a process description, summary tables, and appendices with all PFDs, HMB tables, and cost data bases.
The process design documents presented in the report represent information that can be carried forward to a more detailed mechanical design phase. The purpose of FEL-2 is to provide the process design basis with regard to flow rates, temperatures, pressures, etc. that will be used in further detailed mechanical design. Therefore, the FEL-2 documents define the operating envelope of the demo plant which includes raw material usage, energy and utility usages, and how these inputs are configured relative to the process equipment to achieve final product rates and quality criteria.
- Minerals Processing
- Process design
- Process scale up
- Hydrometallurgy unit operations design