AN IMPROVED 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 at the
Office of the Commissioners of Patents on the 8th February 1878.
CHARLES ANTHONY BURGHARDT, of Manchester, in the County of Lancaster.
AN IMPROVED 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 suffi-
cient 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; 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. The solutions
thus obtained are added to the acid solution before referred to.
The vulcanized india-rubber thus partly purified is gently dried to free it from
water, and then treated as follows, vizt. A quantity of it is placed in a wooden,
copper, iron or leaden double cased steam pan, sufficient "shale spirit," coal naptha,
wood naphtha, petroleum, turpentine, bisulphide of carbon, oil of cautchouc, benzol,
or other solvent of india-rubber is added to it, the pan then securely closed with a
suitable lid, and the whole beated by steam, gas, or hot air, at a temperature not
exceeding 280° Fahrenheit (a temperature of 240° Fahrenheit being the best for
the purpose), until the vulcanized india-rubber has been dissolved or converted into
a thick pasty inass. When this stage has been arrived at the naphtha 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.

page_text: I 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. I also propose to use it (the
said process in the double-cased steam pan) for the more rapid and economical con-
version of ordinary pure unvulcanized india-rubber into a pasty or doughy con-
dition suitable for spreading upon cloth or other material for waterproofing, or other
goods of a similar nature, a great saving in the quantity of naphtha or other solvent
(necessary for the conversion of the said unvulcanized rubber into a pasty state), this
being effected as it takes up as much india-rubber as it possibly can, there being
scarcely any excess of naphtha present.
Treatment of the Solution before mentioned.-This 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 pré-
cipitate the zinc, calcium and lead out of their solutions. I give the preference to
bicarbonate of sodium as a precipitant of the said metals as carbonates. The pre-
cipitate 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 car-
bonate can be either dried and sold as carbonate of zinc, or dissolved in hydro-
chloric (muriatic) acid, sulphuric acid, nitric acid, acetic acid, or other acid, and sold
as chloride or muriate 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.