Precious Metals Recovery LLC RCRA Permit Application Dry Hills ...

Activated carbon is used in the air emission control equipment (e.g., carbon beds) at BGMI, as
well as other Barrick facilities. Spent activated carbon, a mercury-bearing material, will be
shipped to the proposed TSF in 55-gallon steel drums. The drums will be off-loaded from trucks
to temporary storage per procedures outlined in Section 1.2.1. The retort system for the proposed
TSF will be designed to accept feed materials in both 55-gallon drums and vendor supplied retort
trays. The spent activated carbon drums will be transferred to the retort for processing. The
design retort capacity is two 55-gallon drums of spent activated carbon per batch.
Once a batch of spent activated carbon or filter cake is placed on the retort stand and the retort
dome is set, the operator will initiate a pre-determined retort temperature and pressure cycle,
consisting of the following steps:
1. A vacuum will be developed in the sealed retort, which promotes evaporation of volatile
components (e.g., water, mercury, etc.) from the feed.
2. The retort temperature will be increased and maintained at a lower temperature sufficient
to remove moisture from the feed.
3. The retort will be heated to the upper operating temperature to evaporate/sublimate
mercury compounds and will be maintained at an elevated temperature for a fixed period
of time. Near the end of the heat cycle, small amounts of bleed air will be added to the
retort to promote deportment of mercury vapor to the retort off-gas system.
4. After the heating step is complete, the sealed retort will be left to cool. Cooling air will be
drawn into the retort to promote cooling of the retort shell.
The spent activated carbon and filter cake will be processed in separate batches and will not be
mixed as the retort temperature and pressure cycles will be customized to suit the specific feed
material.
After the retort cycle is complete, the drums or retort trays will be unloaded from the retort stand.
The retorted carbon as well as the drums will be tested using EPA methods to determine the
hazardous characteristics and evaluate Land Disposal Restrictions (LDR) standards as described
in Appendix 2-A.
Residues that are determined to be hazardous by characteristics (e.g., do not pass the TCLP test)
or do not meet LDR standards, may be reprocessed or shipped to an appropriately licensed
facility for further treatment and disposal. Other materials will be managed as appropriate (e.g.,
recovery of precious metals, off-site disposal, etc.). Similarly, the retorted filter cake residue will
be tested to determine the hazardous characteristics and appropriate management.
In order for the proposed TSF to reach its maximum throughput of treating 240,000 pounds of
spent activated carbon and 612,000 pounds of calomel per year, two identical retorts will be
required. See H340940-0000-50-042-0002 in Appendix 1-A for a general arrangement of the
process area.
PMR RCRA Permit Application, Dry Hills Facility Page 25
JBR Environmental Consultants, Inc. | HATCH March 2013