IMPROVEMENTS IN THE MODE OF SIZING PAPER AND [IN] THE PRODUCTION OF NEUTRAL SULPHATE OF ALUMINA BY MEANS OF MAGNESIA, AND OF MIXTURES FROM SULPHATE OF ALUMINIUM AND SULPHATE OF MAGNESIUM
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Thomas Morgan at the Office of the
Commissioners of Patents on the 9th October 1883. Communicated to him
from abroad by F. Lienan of Uerdingen [Uerdengen] Germany.
K
THOMAS MORGAN, Secretary of the Inventors Patentright Association Limited,
21 Cockspur Street Charing Cross in the County of Middlesex, IMPROVEMENTS
IN THE MODE OF SIZING PAPER AND [IN] THE PRODUCTION OF NEUTRAL SULPHATE
OF ALUMINA BY MEANS OF MAGNESIA, AND OF MIXTURES FROM SULPHATE OF
ALUMINIUM AND SULPHATE OF MAGNESIUM" (a communication to me from abroad
by F. Lienan of Uerdingen [Uerdengen] Germany)
Instead of the sulphate of alumina (or of the alum) or of the sulphate of zinc,
which are employed in the manufacture of paper for the purpose of sizing with
resin, I make use according to my process, of either a solution of chloride of
magnesium or specially sulphate of magnesia, alone or in combination with
sulphate of alumina (or alum) or sulphate of zinc.-In this way resinate magnesia,
or a combination of resinate magnesia with resinate alumina or resinate sulphate of
zinc is produced, which is indissoluble very glutinous, and in precipitating upon
the paper fibrins intimately connects them in the same manner as was the case
with the process hitherto generally adopted when sulphate of alumina (alam) or
sulphate of zinc alone was used.-The advantages obtained by this new process of
sizing are the following:-
The sulphate of magnesia crystallizes easily and is therefore always of equal
composition and of the greatest purity; at the same time, it does not contain the
least traces of iron and is perfectly neutral
In order to produce neutral sulphate of alumina by means of magnesia, I avail
myself of the following process:-The sulphuric acid acting upon aluminous
minerals, as bauxite, china, clay etc, and the products of reaction being lixiviated,
a lye is obtained which always contains certain quantities of free acid.-This
cannot be separated by crystallization from the sulphate of alumina, on account of
the easy solubility of the latter-With a view to do away with the deleterious
influence of the free acid which partly destroys certain colours, especially ultra-
marine, and azo colouring matter, partly preventing the paper being well and
perfectly sized, a quantity equivalent to the free acid of magnesia, hydrate of
magnesia, or magnesite in a pulverized state, is added to the raw sulphates-The
מ.

page_text: mixture is then lixiviated with hot water, the free acid being neutralized by the
magnesia.
I obtain in this way a very sticky lye which has not any influence on the most
tender azo-colours and ultramarine, besides improving the sizing capacity of the
product by the magnesia contained in it.
The lyes are thickened by evaporation to a specific weight of 1.5167 to 1.5820
(50° to 54° B) and cast in sheets to be cooled.
The process employed in producing mixtures of sulphate of aluminium and
sulphate of magnesium is based on the fact that the solutions of these two salts,
when thickening by evaporation and cooling, produce mixtures of the two bodies
which, according to the quantity of the two components, allow of being either cast
in sheets or precipitated as crystalline powder. To produce these mixtures, a
solution of sulphate of aluminium is first prepared, by fluxing in the known
manner, aluminious minerals, as china clay porcelain clay, and especially bauxite,
with diluted sulphuric acid, lixiviating the porous mass produced with hot water,
and clarifying the solution by permitting the same to subside, or by filtration.
The clear lye is employed either directly, or it is neutralized, and if requisite, the
iron precipitated. After that, the Kieserite is dissolved in water, and a clear and
possibly rich solution is prepared thereof by decantation; the two solutions are
then mixed in proportions which are in conformity with the kind of paper for the
sizing of which the product is to serve, thickened by evaporation to the specific
weight of 1.515 to 1-596 at 100° Cels., and let off for cooling whereby the solution
becomes stiff, forming a homogeneous mass.
The raw sulphate mixed with the given quantity of Kieserite may of course be
directly lixiviated, clarified and thickened by evaporation.-The Kieserite contains
however, small, quantities of chloride of magnesium, which, together with the
sulphate of iron contained in the sulphate of aluminium of an inferior quality, is
changed to sulphate of magnesium, and proto-chloride of iron, or perchloride of
iron. These salts are of a considerably more intense color than the respective
sulphates, so that the article, when containing 1% of iron, has a strong greenish
colour.
In order to prevent this, bitte salt is taken in place of the Kieserite which is
best carried out by adding to a certain quantity of lye from alumina contained in
the boiling pan, the previously calculated quantity of bittersalt. In the manu-
facture of paper for writing, drawing and printing purposes, an extremely small
addition of alumina to the bittersalt leads to very favorable results. For the
production of a preparation which is suitable for the purposes just referred to, the
solution of Kieserite is best thickened by evaporation to the specific weight
of 1.442.
The solution is subsequently brought into flat vessels; to every ten cubic metres
of this liquid 500 litres of a saturated solution of sulphate of aluminium is added,
and the whole stirred up until it has become cool
The bittersalt is thereby separated as a fine white crystalline powder, which is
removed by means of a centrifugal machine making 1000 revolutions per minute.―
Produced in this manner it contains 1 to 2% of alumina, and in precipitating with
resin soap, gives a precipitate which is extremely voluminous and very sticky.
The advantages which these mixtures offer as compared with the employment of
sulphate of aluminium are a cheaper price, greater purity, and when containing
the same amount of oxides, an increased sizing capacity, because of the very
glutinous nature of all combinations with magnesia