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Technical Summary of PRO-pHx as used by Thermal
Metal Treating, Inc.
Thermal Metal Treating, Inc. has been using PRO-pHx
since October 2001. The principle application has been as a purification
additive for acids. HCl acid is used in the processing of stainless
steel black oxide, ferrous metal black oxide, zinc phosphate, iron
phosphate and manganese phosphate heat-chemical coatings. The HCl
acid is used for the pickling and activation of carbon steels and
stainless steels and/or the stripping of coatings such as zinc from
various base metals.
The examples shown in the charts are for the two black oxide lines
in which the HCL tanks are 125 and 225 gallons respectively. The
tanks were first made up at 50% HCL acid at 20 degree Baume (by
volume) and 50% water. They have been maintained at 40% to 50% acid
and 1% PRO-pHx (by volume) and filtered since October
Prior to using the PRO-pHx additive, higher than
legal threshold levels of chrome showed up in the subsequent rinse
tanks for the stainless steel black oxide line. Zinc and iron were
also measurable throughout the rinse system on the ferrous line.
Additionally, both HCL tanks were (Quarterly) waste treated because
of the heavy concentrations of dissolved metals and organics.
Since using the PRO-pHx additive there is no appreciable
chrome in the rinses systems, and the acid tanks no longer
require waste treatment. The required maintenance is to: 1.
Titrate the acid and make additions to maintain concentration. 2.
Add 1 part PRO-pHx to 100 parts acid (by volume) when
adjusting the acid concentration. 3. Continuously filter the acid
tanks with a 10-micron cartridge filter and clean the filter weekly.
Note: Any type of filter will suffice once you find the micron size
best suited for your use.
The addition of PRO-pHx to these systems has resulted
in a 96% reduction in hazardous waste (by weight), reduced
system downtime for maintenance, reduced HCL acid use, reduced sodium
hydroxide (for pH adjustment) use, less water use for rinsing due
to the rinses receiving less contaminants, less use of the waste
treatment system and the obvious reduction in waste treatment labor
TMT, Inc. is currently installing a simple filtration system, using
the PRO-pHx additive, with intentions to also bring
the rinses on the plating lines to zero discharge.
The following are the findings of Aqua Tech Environmental Laboratories
Inc. of Marion Ohio. These figures are taken directly from their
Certificates of Analysis. No chromium or zinc figures for the plating
rinses are available prior to PRO-pHx use, because
the heavily contaminated rinses were simply sent to the waste treatment
system. There the chrome was reduced to the trivalent state and
a standard pH adjustment, flocculation, filtration and independent
lab testing were performed before the water was disposed of to the
city sewer. After 9 months of similar positive findings, Thermal
Metal Treating, Inc. was no longer required to use an independent
laboratory for testing of the waste stream and currently does simple
in house testing before rinse disposal. Note: UG/L = parts per billion.
Post HCL rinse on the Stainless Steel Black Oxide line after
9 months of PRO-pHx use
Post HCL rinse on the Carbon Black Oxide line after 9 months
of PRO-pHx use
Summation: Filtration of acids has lowered our operating costs,
reduced our solid waste generation and eliminated independent lab
testing of the rinse streams.
Thermal Metal Treating, Inc.