The following is from the Precious Metals West Home Page:
(My name is Tom, and I’m a Web-aholic.)
In a Pickle (or: No, the toilet is NOT legal waste disposal. ) by
Whether they work in precious or costume jewelry, every bench
jeweler utilizes a basic pickle pot to clean the oxides, dirt and
grease from his or her work. In some shops, there is a community
pot for the use of all the bench workers on the premises, but
most often, each jeweler maintains his or her own.
The pickle is always acid-based. Some use sulfuric, dilute
nitric or hydrochloric acid. I recommend a light, dry acid
compound such as sodium bisulfate. This is much safer than the
stronger acids, and is quite effective.
Now for the $64,000 question (or whatever the fine is): What do
you do when your pickle is worn out and contaminated with
silver, copper and zinc? Many simply choose to dispose of the old
pickle bath and start a new one. And unfortunately, in all too
many cases, this means the pickle gets poured down the drain or
dumped into the toilet. Naughty, naughty, naughty…
Such behavior is in direct violation of a host of local and
federal environmental laws, and effectively makes you a common
Time-consuming and costly though it may seem, you have to
legally dispose of any corrosive waste, such as pickle, from your
shop. But here’s a look at a technique you can use to reduce the
frequency with which you have to dispose of your pickle, thereby
reducing some of the headaches of waste control and disposal.
(This comes by way of my good friend Dominic Anetta of DoPaso
Inc. in Albuquerque, NM.)
The process is called “electrowinning.” In electrochemical
terms, a “used” pickle solution consisting of acids and metals
can be thought of as a simple plating solution. Through
electrowinning, you can “plate” much of the metal contaminants
out of your pickle solution, allowing you to reuse the pickle a
number of times before you have to dispose of it.
The process involves the use of a plating rectifier, or a
six-volt car battery charger capable of producing at least five
amps. A base metal cathode (typically a copper strip) is
connected by clips and wire to the negative (-) terminal of the
rectifier. A graphite anode is similarly attached to the positive
(+) terminal (graphite stir rods available from most jewelers’
supply houses work great). Suspend the cathode and anode
separately in the solution, and activate the charger.
The metals will “plate” onto the copper cathode, and can easily
be scraped off when the process is finished. You will also find
a flaky metal sludge at the bottom of the container&emdashthese
flakes fell off the cathode during electrowinning.
Pour off the clear pickle into a second container, leaving the
metal sludge behind. The pickle solution is regenerated in this
process, and can be reused many times. Of course, not all metal
will be removed by this process, but you only need to remove most
of it to regenerate the acid. Some carbon will be imparted into
the solution from the20 graphite anode, but it will settle out
and have no effect on the pickle acid.
Because the metal residue is corrosive, you should rinse the
sludge and scrapings with water. This rinse can then be used to
top-off the regenerated pickle solution. After rinsing, the
sludge and scrapings should be allowed to air dry, and then
placed into proper storage until sufficient quantity is obtained
to send to an EPA registered disposal service.
Now, the sniveling cowards who edit this magazine insist that we
point out that this column is only an overview of electrowinning.
There are numerous cautions and concerns we don’t have room to
address, such as proper handling of the rectifier/charger, and
proper handling of acids. In addition, pickle salts for use on
nickel silver20 which contain chromium (a toxic metal) create
problems both in electrowinning and disposal.
So before adopting this process, you must contact your local
environmental authority. Most states have a non-regulatory agency
that can guide you through these processes. They can also provide
disposal and inform you of the nearest licensed
hazardous waste disposal site.
Remember though – the toilet is not an option. Even if you
think you’ll never be caught – even if you do it at 3 a.m. and
follow the flushing with massive doses of bleach and soda. Guilt
and social consciousness are powerful emotions – ones you don’t
want nagging at you (remember Jiminy Cricket?).
It is far better to live clean&emdashand far less costly than
being fined or jailed for not knowing what to do. Besides, life
in jail can be thoroughly disgusting. (Even if you’re not a
former pro football player.)
Marc Robinson is co-owner of Precious Metals West/Fine Gold, a
metals refiner and fabricator based in Los Angeles. For a paper
outlining the electrowinning process in more detail, contact
Robinson at (909) 923-4203.
Sniveling Editor’s Note: The use or application of
practices and/or techniques pertaining to jewelry manufacturing
or jewelry repair or other related topics contained in this
publication (the ") may be hazardous to persons and
property. Any use of the in jewelry manufacturing or
repair, or otherwise, is undertaken at the reader’s own risk. ~
154 AJM B7 March /1995
Precious Metals West / Fine Gold20
608 S. Hill St. #40720
Los Angeles, Ca. 9001420
1-800-999-7528 / 213-689-487220