Making chlorate and perchlorate
This file has two parts... the first is predominantly about
KClO4, and the second about KClO3. Both were taken from the
net, original sources unknown.
MAKING POTASSIUM PERCHLORATE
This proceedure is a "tried and true" method. Unlike
some rec.pyro postings, which are informational, or just
plain speculative, this proceedure WORKS. I have used it
myself to make my own supply of perchlorate - until I
decided to quit because I was making it far too fast to use.
This proceedure works well to make chlorates as well. The
proceedure can be modified easily to make only chlorates.
When using this proceedure to make perchlorate, it produces
significant amounts of chlorate as a by-product. This is
because carbon rods are not highly efficient in converting
chlorate to perchlorate. Other anodes work better, but this
proceedure was designed using easily available common
materials and supplies.
--- Author
Carbon Rods
Get some carbon rods from the welding shop. They are made by
"arcair", and are 3/8" diameter by 12" long, and cost between
40 to 60 cents(US) each. They are copper plated, and they are used
for a welding proceedure known as "gouging".
Cut off the top of a plastic 1 gallon milk jug. This is a
good cheap source of containers for using in this proceedure.
Dissolve 1/2 cup of salt in 2 liters of warm water. Put this
in a small plastic container. Cut out a piece of coffee can,
roughly 4" by 4" with a tab extending up to connect a wire to.
The dimensions are not critical. With a 6 volt battery charger,
connect the minus (-) connector to the piece of coffee can.
Wrap some aluminum foil on the end of the carbon rod, to improve
the electrical connection, and connect the plus (+) connector
of the charger to it.
Turn on the charger, and let it run for about 20 minutes. The
copper will be removed from the rod. If some still remains,
run it for a little longer till it is free of copper.
Discard the salt water used to remove the copper.
<p>You can probably use a 12V charger, but the current may get too
high, so you may need to reduce how much of the rod is being
etched at one time.
Electrolyte solution
Make a mixture of salt and potassium chloride solutions.
Dissolve roughly 2 ounces (60 grams) of salt, and 8 ounces
(240 grams) of potassium chloride in 2 liters (just a bit
more than 2 quarts) of hot water. There is much room for
inaccuracy here, because the exact mixture is not absolutely
critical.
At this point, it is good to add between 2 to 10 grams of
either potassium chromate or dichromate. While this is not
absolutely necessary, it helps improve how much perchlorate
is finally produced. The process will work without it, but
not quite as well.
NOTE: Potassium chloride can be obtained as several commonly
available products, such as: dietary salt substitute,
ice melter (look at label for actual contents), and
"muriate of potash" from farm and garden supply shops.
Hagenow Laboratories carries potassium dichromate.
The reason a mixture of salt and KCl is used, is two fold.
First, salt is more easily electrolyzed than KCl, but after
it converts to chlorate (and perchlorate), it will tend form
the potassium salt instead of the sodium salt. The electrolysis
tends to work on the sodium salt, while the final potassium
perchlorate forms, and due to it's poor solubility, tends to
crystalize out of solution. Secondly, the concentration of
KCl is chosen to help prevent chlorate from crystalizing out,
while being too high for the perchlorate to remain in solution,
which causes it to crystalize out as it is created. These
concentrations may be varied, to compensate for different
operating temperatures. It was designed to operate at 40C, and
will work fine above that temp, but below it, you might get
some chlorate crysatlizing out, in which case you might need to
reduce the amount of KCl just a little.
I have been using a little salt in my mixture, but someone could
exclusively electrolyze KCl, without the addition of salt. The
purpose of the salt is to provide a sodium salt which is more
easily electrolyzed than the potassium salt. It is NOT necessary,
and will probably work well with only KCl.
****** (Chlorate note) ******
BTW, chlorates are produced here as an intermediate chemical
product. Chlorates tend to be the predominant component around
1 1/2 to 2 days of operation. Chlorate could be caused to
crystalize out during electrolysis if the concentration of KCl
in the starting electrolyte solution is increased to nearly
saturation (about 21 ounces KCl/ with 2 ounces of salt). Although
I have not concentrated on chlorate production, I would expect that
you could actually run it for more than 2 days - possibly up to
4 or 5 days, and keep building up a layer of largely chlorate
crystals on the bottom. In that case, I would _GUESS_ that you could
get around 2 pounds of chlorate after 5 days of operation.
Electrolysis
Using a coffee can for a source of steel, cut it out to form
an inverted U shaped trough. Insert it in the mixture of salt
and KCl dissolved in water. The (-) connector is connected to
the steel. The steel U trough (similar to a rain gutter, except
upside down) is setting at an angle to increase the amount of
surface area in contact with the liquid. The carbon rod has
some aluminum foil wrapped around the end of the rod, and the (+)
connector is connected to it. The rod is positioned within the
U shaped trough - under it, without touching. The charger is
turned on, and he position & depth of the rod is adjusted to
get 8 to 12 amps of current.
NOTE: A setup with the electrodes running electricity through
an electrolyte is called a "Cell". This setup is commonly
refered to as a cell throughout this description.
Let the liquid electrolyze for about 5 days continuously.
Add water to make up for water lost during the process, and
try to keep it roughly constant.
A couple times a day, you will need to check the current level,
and adjust the rod position to keep the current in the 8-12amp
range. Mine has been running between 40 - 50C, but commercial
proceedures keep the temp just below 40C to reduce carbon rod
errosion. The rods will gradually errode away, but if you use
a 6V charger, one rod will probably last for the full 5 days.
You can also use higher voltage chargers, but you will probably
need to connect several electrolytic cells together to keep
the voltage accross ONE cell to be about 6 volts. If you use
a 12 V charger, you will need 2 cells ( 12V/(6V per cell) = 2cells).
If you connect more than 1 cell in series, you may need to use
a voltmeter to check the actual voltage accross each cell - because
it will change depending upon the resistance differences between
the cells, which can be adjusted by re-positioning the rods.
The purpose for the U shaped trough cathode (-) electrode, is to
cause the gas bubbles formed to generate a convection flow up
through the trough. This causes the chemical products produced
at each electrode to mix and react efficiently. Other electrode
geometries will work, some better, and others worse. The key
is to cause the two electrodes to be very close to each other,
and cause the chemical products to mix well to help form chlorate
and perchlorates. The WORST case situation is where the electrodes
are on opposite sides of the cell, causing the chlorine gas
produced at the anode (+) to tend to bubble and escape
out of solution into the air.
Crystalization
The potassium perchlorate crystalizes out
as it electrolyzes. When you're done, you have a mixture of
black carbon, perchlorate, and some chlorate after you drain
off the liquid. I generally get a layer of perchlorate
crystals about 1 inch (2.5cm) thick on the bottom, which tends
to be about 1 pound.
Cool the liquid in a freezer to help increase the amount of
perchlorate that is crystalized out, before draining the electrolyte
liquid. When draining the electrolyte, save it if you want to
re-electrolyze it to make even more perchlorate again.
Load the crystals into a filter, and use boiling water to
dissolve the perchlorate out. As it filters, the perchlorate forms
nice flat rhombic shaped (almost square) flakes that float out of
solution. You watch it as it cools, and watch for chlorate crystals,
which tend to look like clusters of cactus needles. When they
start to form (well after the perchlorate has largely
crystalized out), you drain the liquid, and add some room
temp water which is to be about 2 - 3 times the volume of the
crystals you have in the container. Shake them, and let it
stand overnight to dissolve any chlorate crystals. Then
drain, wash (with ice cold water), and dry the crystals.
NOTE: Coffee filters generally aren't good enough to filter out
the black carbon particles. You can load a coffee filter
with a good layer of diatomaceous earth, and then use it
to filter the liquid. Diatomaceous earth is used to filter
swimming pool water, and a 10 pound bag can be obtained
for less than US$10.00.
You can purify them again by weighing the dried crystals,
and adding enough water to dissolve the whole mass as if it
was pure chlorate (i.e. 7g/100ml water)*. Use hot water, and
then cool it down to room temp. You might even need to cool
get the perchlorate to begin to crystalize (it seems to
super saturate commonly). You might be able to get it
started by adding a small amount of perchlorate dust as
crystal seeds - if you have some to start with.. Then wash
your crystals (with ICE COLD water), and dry them. That will
help produce a higher purity product of perchlorate. If you
want to make a chlorate-free batch of perchlorate, repeat this
process again. It will be essentailly free of chlorate if you
double crystalize it, and make certain you wash the crystals
several times with cold water.
Example: 100 grams of crystals would require
100grams/(7gm/100ml) = 14.3 (100 ml), or 1430 ml of water,
or about 48 ounces.
NOTE: When harvesting the crystals, a cotton cloth makes a
good filter. I wear rubber gloves, and squeeze the excess liquid
from the crystals before & during washing them. Squeezing
helps remove additional contaminants which are dissolved
in the liquid that wouldn't otherwise be removed by
simple gravity filtering. While this method loses very
small crystaline particles, the loss tends to be very small
in comparison to the amount of crystals harvested.
Perchlorate is very easy to make, but it takes a little
work. The hardest ingredient to get is patience.
WARNINGS
This proceedure generates small amounts of chlorine gas, as well
as hydrogen gas. It should be conducted outdoors, or in a well
ventilated building which is NOT used for living quarters! Hydrogen
can accumulate in non-ventilated and sealed rooms to form potentially
explosive mixtures with air!! Chlorine generally is more of a
irritant, but can be poisonous at high concentrations. There are
also other (?) chlorine oxides and/or ozone produced which should
also be avoided.
Chlorates and perchlorates are NOT chemicals for playing!! They
are serious oxidizing agents which can be used to make VERY DANGEROUS
pyrotechnic mixtures - _ESPECIALLY CHLORATES_ !!! Be certain to
read up on all litterature describing the use and dangers of these
compounds! It is VERY EASY to forget the safety hazards associated
with these oxidizers in a time of haste - and lose a limb or your
life as a result of your forgetfulness! Be careful to clean up
any oxidizer which is spilled on carpets, or solutions which have
spilled or splashed on any form of flamable material, including
clothes, wood, paper, etc.
CHLORATES ARE ESPECIALLY FRICTION AND SHOCK SENSITIVE!
PERCHLORATES CAN ALSO PRESENT THE SAME HAZARDS, BUT NOT AS
BADLY AS CHLORATES!
ALSO, AVOID THE DISASTEROUS MIXTURE OF CHLORATE WITH SULFUR.
NEVER MIX EITHER OF THESE WITH ANY FORM OF PHOSPHORUS, AS IT
CAN IGNITE OR EXPLODE BY THE FRICTION OF SIMPLY MIXING THEM!!!!!
Also, chlorates must be kept from any form of acids, especially
sulfuric. Even small traces of acids (from the presence of sulfur,
etc) can cause what "appeared" to be a stable mixture, to ignite at
some unknown time later!