PROCESS FOR THE UTILIZATION OF THE INDIA-RUBBER CONTAINED IN WASTE VULCANIZED INDIA-RUBBER GOODS, AND THE RECOVERY OF THE ZINC PRESENT IN SUCH WASTE GOODS; ALSO FOR THE TREATMENT OF UNVULCANIZED INDIA- RUBBER
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Charles Anthony Burghardt, Thomas
Rowley, and Arthur Critchley Salomonson at the Office of the Commissioners
of Patents on the 12th June 1878.
CHARLES ANTHONY BURGHARDT, THOMAS ROWLEY, and ARTHUR CRITCHLEY
"AN IMPROVED.
SALOMONSON, all of Manchester, in the County of Lancaster.
PROCESS FOR THE UTILIZATION OF THE INDIA-RUBBER CONTAINED IN WASTE
VULCANIZED INDIA-RUBBER GOODS, AND THE RECOVERY OF THE ZINC PRESENT
IN SUCH WASTE GOODS; ALSO FOR THE TREATMENT OF UNVULCANIZED INDIA-
RUBBER."
The clippings are thrown into a wooden or leaden vat, and covered with a
sufficient quantity of hydrochloric acid (muriatic acid) of such a strength as will
ensure the complete destruction of the cloth and fibre adhering to the same, and
boiled by steam applied outside the vat, or by coiled pipes inside the same, or else
by waste heat from a furnace.
The boiling is continued until all the cloth fibre is destroyed, and the vulcanized
india-rubber is free from fibre.
The acid solution contains chloride of zinc and chloride of calcium, also occasion-
ally chloride of lead and other substances or compounds; it is treated as herein-
after described.
The vulcanized india-rubber obtained as above is now thrown into a vat con-
taining water, and is boiled to free it from adhering acid and any zinc chloride,
calcium chloride, or other chloride also adhering to it, this operation being repeated
until the vulcanized india-rubber is clean and free from acid and fibre.
solutions thus obtained are added to the acid solution before referred to.
The
The vulcanized india-rubber thus partly purified is gently dried to free it from
water, and then treated as follows, vist. :-A quantity of it is placed in a wooden,'
copper, iron, or leaden double-cased steam pan. Sufficient "shale spirit," coal
naphtha, wood naphtha, petroleum, turpentine, bisulphide of carbon, oil of cautchoric,
benzol, or other solvent of india-rubber, is added to it; the pan is then securely
closed with a suitable lid, and the whole heated by steam, gas, or hot air at such a
temperature that the vulcanized india-rubber will be dissolved or converted into a
thick pasty mass. When this stage has been arrived at the naphtha or other
Duine 71

page_text: solvent is evaporated off or condensed in a suitable condensing apparatus if the
quantity is great. The temperature at which the evaporation takes place must not
exceed 212° Fahrenheit.
We propose to apply the process in the double-cased steam pan to the conversion
of all kinds of waste vulcanized india-rubber goods (such as old railway engine
buffers, valves, and so forth) into a pasty condition, such as that described in the
case of the vulcanized india-rubber obtained from the clippings. We find it better
in such cases to reduce the rubber to a state of "crumbs," by grinding between
friction rollers or otherwise, before submitting it to this process.
We also find it convenient in some cases to submit it to the acid process above
named in order to remove metallic compounds.
We find it better for some descriptions of waste rubber to boil the same in linseed
oil or other vegetable drying oil, by which it is reduced to a doughy state, instead
of using a spirituous solvent. The rubber when so treated we place in a vessel
containing an agitator, and add a sufficient quantity of a moderately concentrated
solution of caustic soda, caustic potash, ammonia liquor, caustic lime, carbonate of
soda, carbonate of potash, carbonate of ammonia, carbonate of lime, or carbonate of
magnesia, or any mixture of two or more of these ingredients (but we prefer to
use caustic soda or carbonate of soda) to extract the oil by boiling the same together
therewith and converting it into a soap. The rubber residue is then well washed,
either by boiling in water or by passing it through rollers whilst water is running
upon it, or by any other suitable ineans.
When the rubber has been thoroughly cleansed and dried we mix therewith such
mineral substances as are ordinarily employed by india-rubber manufacturers,
according to the purpose for which it may be required, and when required for
spreading upon cloth for waterproofing purposes we add a sufficient quantity of
mineral naphtha or other solvent above enumerated to reduce it again to a pasty
state, and when so prepared we vulcanize it in the ordinary way, according to the
class of goods required.
For some purposes we find it convenient not to boil out the oil as above described,
but to add to the oil and rubber a sufficient quantity of litharge or black oxide of
manganese to cause the rubber to dry rapidly.
Treatment of the Acid Solution Before Mentioned.-The solution is treated in a
vat with a sufficient quantity of bicarbonate of sodium, soda crystals, anhydrous
sodium carbonate, ammonium carbonate, potassium carbonate, the carbonates of the
alkaline earths, caustic soda, caustic lime or its solution or caustic potash, to pre-
cipitate the zinc, calcium, lead, and other metallic substances out of their solutions.
We give the preference to bicarbonate of sodium as a precipitant of the said metals
as carbonates. The precipitate is allowed to settle, and then the supernatant liquid
is run off.
When sufficient precipitate is obtained in the vat to make it worth
while to treat further it is levigated with water, by which the carbonate of calcium
is carried away, owing to its specific gravity being less than that of carbonate of
zinc.
The zinc carbonate can be either dried and sold as carbonate of zinc, or dissolved
in hydrochloric (muriatic) acid, sulphuric acid, nitric acid, acetic acid, or other acid,
and sold as chloride or muiate of zinc, sulphate of zinc, nitrate of zinc, acetate of
zinc, or other salt of zinc.
The original acid solution may also be simply concentrated down to a suitable
degree of Twaddle's hydrometer, and sold for mixing in the size applied to cotton
and other goods as an antiseptic for mildew; or the precipitate may be simply dried
and used over again for mixing with india-rubber.