NCS000583_2019 Staff Report_20200401

NC Division of Energy, Mineral and Land Resources
Review for Permit — NCS00583
Metallix Refining
Facility Activities and Processes:
• New Permit — Submitted in 2015
• SIC Code — 3341: Secondary Smelting and Refining of Nonferrous Metals
• The facility performs precious metal recovery from scrap.
• Metallix is a specialty company that recovers and precious metals from various types of
industrial and commercial waste products. Some of the precious metal is refined to high purity
for sale, and some is sold at lower purity to others for refining and further processing. The
precious metals recovered include: gold, silver, palladium, platinum, and rhodium. The sources
of the raw materials used in Metallix's processes are diverse industries manufacturing and/or
recycling materials used by consumers on a daily basis. Examples of the types of products
involved, but my no means a comprehensive list of them, include automotive, fine china,
photography, medical imaging, consumer electronics, and jewelry.
• The raw materials received include dry solids, sludges containing both solid and liquid fractions
and liquids. These materials are purchased based on the precious metal content of the material
and the seller is paid based on the amount of precious metal that can be recovered. The
different raw materials are processed through the plant based on their physical and chemical
characteristics. There are many variations possible in the process used, but the following
characterization is typical:
o Solid Materials: Sludges, film, wiping rags from the manufacture of fine china, and other
solid materials that contain precious metals, are processed in high temperature furnaces
in the absence of oxygen. The ash from these furnaces is sent to milling where it is
reduced to a fine powder that may be blended, assayed and sold. Selected lots may be
sent to the Liquids Department where it is dissolved, and the precious metals plated
out. Selected metals may also be melted and formed into ingots, which are sold. The
fine dust from this process, a potential air pollutant, is captured in a high (>99%)
efficiency bag filter and is returned to the process. A liquid scrubber cleans the exhaust
gasses in accordance with the plant's air quality permit.
o Liquid Materials: spent plating baths from gold of silver-plating operations are
processed to recover the traces of precious metals remaining. They may be plated out
or may be separated chemically by selective precipitation and filtration. The sludges and
filters are processed through the furnaces. Spent liquids are treated to remove any
other metals, such as copper or arsenic that may be present. The resulting sludge is
disposed of a s a hazardous waste. If the residual liquid contains cyanide, it is shipped
off site for treatment and disposal. Residual liquids that are not hazardous wastes and
that meet the criteria established by Greenville Utilities are discharged to the public
sewers after testing and approval.
o Raw Material and Intermediate Product Handling: The raw materials received are
handled properly to insure that they are processed in the most efficient manner to allow
the recovery of the precious metals they contain. Raw materials are received by truck
and are unloaded at a covered loading dock and are stored inside the building where

they are staged for processing. No raw materials are stored outside or in an uncovered
area where they may be contacted by rainfall. Intermediate products are also handled
totally inside the building with two possible exceptions. The first exception is the dust
from baghouses. The captured dust contains precious metals and it is returned to the
process so that these metals can be recovered. However, the handling of the dust
creates the possibility that the dust may be contacted by rainfall. The baghouse dust is
discharged into a closed container underneath the baghouse. Each container is picked
up and moved into the building as it becomes full. It is possible that during the switching
of the containers, a small amount of dust may escape and be discharged to the ground.
If this occurs, then it could be contacted by rainfall and be washed into the stormwater
discharge. The blowdown from the liquid scrubbers that control the emissions from the
furnaces is also captured and is currently returned to the process where it is
evaporated. Normal practice is to store the captured liquid inside the building, but is has
been stored outside for short periods of time. This raises the potential that any residue
on the storage container could be washed off by rainfall and be discharged with the
storm water. Future flows of the scrubber blowdown will increase as the new furnace
achieves full operation, so Metallix is investigating the feasibility of discharging the
scrubber blowdown to Greenville Utilities.
o Empty Containers: Empty containers that held raw materials are normally stored inside
the building. On rare occasions, some have been stored outside. These containers are
normally clean, but if any residue of the raw material were present, it could be
contacted by rainfall and introduce a pollutant to stormwater runoff.
o Site Description: The site drains to ditches on the west and east sides of the site, which
then drain to a ditch along the north side of the site. This drainage ditch system is part
of an area -wide ditch system that is a UT to Parker Creek. The grassy area of the site is
not impacted by any industrial activity. A broad drainage swale is located through the
grassy area that collects rainfall runoff and conveys it to the north property line. Since
this drains an area not impacted by industrial activity, and since it is a grassed drainage
feature, it is not listed as a stormwater outfall point. All of the stormwater impacted by
industrial activity discharges to the drainage ditch along the east side of the property.
The paved areas and roof surface areas are drained to drop inlets, which in turn
discharge to the drainage ditch. The point where this ditch leaves the property at the
northeast corner is considered the stormwater outfall point.
o There are no vehicle maintenance operations conducted on site that could result in the
discharge of pollutants to the stormwater drainage system.
Monitoring Information:
• The site has one industrial outfall that drains to Parker Creek.
• Scrap metal is used at the facility: TSS, COD, Copper, Zinc, and pH have been added to the permit.
• The facility discharges to nutrient sensitive waters. Phosphorus and nitrogen have been added to
the permit.
• The facility recovers gold, silver, palladium, platinum, and rhodium. Silver has been added to the
permit.

Impairment:
• Parker Creek is an impaired water, experiencing problems with benthos, fish community, and
fish tissue mercury.
• The 2004 basin wide plan for the Tar -Pam basin shows impacted water quality in Parker Creek;
however, data from 2007 shows significant improvement for most all indicators surveyed.