APPLICATION OF THE DOUBLE ALUMINUM AND AMMONIUM SULPHATE

IN THE PAPER INDUSTRY

By Adolfo Rios Pita Giurfa

Spanish-Espaņol

History

In the nineteenth century paper manufacture industry used natural aluminum ammonium sulfate , the mineral known as "Tshernigite", or the other natural alum, double aluminum and Potassium Sulfate.

When the Bayer process for the extraction of aluminum from bauxite appeared, it began to be used the artificially obtained Aluminum Sulfate instead.

We all know that books from the 18^th.century, made from natural alum, are extraordinarily well preserved in libraries book shelves, in contrast with those books made from papers obtained with the use of simple aluminum sulfate.

As it is well known double aluminum sulfates are made from simple aluminum sulfates, then logically are more expensive than the simple ones.

In 1986 it was found at Cerro Verde Mine ( a copper mine ,located at the south of Peru, then state owned, and where solvent extraction methods were applied for the extraction of copper from acid leaching liquors of copper oxides ) that the content of aluminum in the "raffinate" liquors was as high as 12 grams per liter and this was interfering with copper extraction efficiency. Then it was proposed to separate this aluminum precipitating it as double aluminum and ammonium sulfate using ammonia for this purpose. We then suggested the use of the fertilizer ammonium sulfate to attain this goal, since it was cheaper and it was not needed to build a plant for the production of ammonia.

A pilot plant was constructed and the product obtained in this plant was being sold, through a dealer, to local paper manufacturers. This plant was closed before the mine was privatized, and stopped producing the aluminum-ammonium double sulfate.

The aim of this page is to call the attention to what was found in the actual application of the double aluminum sulfate in the paper industry.

It was found the following:

• Double sulfate was used in 30% less per each ton of paper compared to simple aluminum sulfate.
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• Drying of "stock" was accelerated , then saving steam energy expenses.
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• Fiber dispersion was even.
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• Paper impermeability to water was considerably increased.

Since this plant closed the dealer was deprived of this product and contacted us to obtain it; but not having access to the same cheap source of aluminum we sought and found another cheap source: the effluents of an activated clays factory. But we really used a simple aluminum sulfate recovered by this company, and to obtain it at the cheapest cost we obtained the double aluminum and ammonium sulfate through a "DRY REACTION", by mixing dry aluminum sulfate and ammonium sulfate in an helicoidal mixer with the stoichiometric amount of water, as follows: