IMPROVEMENTS IN THE UTILIZATION OF BLAST FURNACE SLAG RICH IN ALUMINA, AND IN THE MANUFACTURE OF ALUM AND BY-PRODUCTS
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by William Jones at the Office of the
Commissioners of Patents on the 27th May 1878. A communication from
abroad by Herr Friedrich Bangert, of Beuel, in the Empire of Germany.
WILLIAM JONES, of Middlesborough, in the County of York, Chemical Manu-
facturer, "IMPROVEMENTS IN THE UTILIZATION OF BLAST FURNACE SLAG RICH
IN ALUMINA, AND IN THE MANUFACTURE OF ALUM AND BY-PRODUCTS." A com-
munication from abroad by Herr Friedrich Bangert, of Beuel, in the Empire of
Germany.
For the purpose of alum making I prefer slag rich in alumina, but other minerals
rich in alumina and capable of being acted on by weak hydrochloric acid can be
used in my process. In using slag however it must be first disintegrated. This is
best done by pouring it in the heated state into water, when it will of itself crumble
up into sand.
The utilization of the slag is as follows, the quantities and manipulation here-
after mentioned being those best adapted, as far as I am at present able to ascertain,
to a slag containing equal quantities of alumina and silica; the exact quantities
will of course vary with every composition of slag or other mineral used:-The
powdered or disintegrated slag is put into a cistern of stone or other suitable
material, provided with a cover and arrangement for disposing of any noxious gases
evolved in the process along with hot muriatic acid of about 15° Beaumé, in the
proportion of about two hundred and fifty pounds acid per one hundred pounds
slag, well stirred up, and left to digest. The mass effervesces and heats, giving off
considerable volumes of gas and vapour.
If the operation has been properly conducted the result on cooling is a dry crumbly
mass, consisting practically of aluminum chloride, calcium chloride, and silica
rendered insoluble. The mass is then treated with water, which dissolves out the
soluble salts, leaving the silica, requiring only to be dried and freed by calcining
or other suitable means from any adherent sulphur precipitated with it, to be a
marketable article.
The exact quantity of calcium chloride present in the solution after removal of
the silica having been ascertained, the quantity of sulphate of magnesia necessary for

page_text: its decomposition is added in the shape of a perfectly clear solution of kieserit
(mineral sulphate of magnesia) of 15° Beaumé, which precipitates all the lime
present in a sulphate, which separated from the mother liquor, thoroughly washed,
and dried, is a perfectly white sulphate of lime, known as pearl hardening.
After precipitation of the calcium from the solution, and the determination of the
chloride of aluminum present, there is added,―
1st. A clear solution of muriate of potash of 25 degrees Beaumé, in the propor-
tion of one equivalent of potash to one of alumina.
2nd. A clear solution of kieserit of 33 degrees Beaumé in the proportion of
three equivalents sulphate magnesia to one of alumina. (If preferred these sub-
stances may be dissolved, directly in the mother liquor, but heating and settling are
requisite to get rid of impurities, and the product must also be thoroughly washed,
or even re-crystalised.).
After concentration by evaporation if required the alumina is precipitated on
cooling in combination with the other elements as a fine white alum in powder,
which is collected, washed with a little cold water, and dried by a centrifugal
machine or other suitable means.
The making of alum by the addition of muriate of potash and sulphate of
magnesia to sulphate or chloride of aluminum solutions is applicable to the manu-
facture of alum, as at present carried on, the quantity of sulphate of magnesia liquor
to be added being of course proportionate to the quantity of chlorides to be decom-
posed, according as the aluminum salt is sulphate or chloride.