ITCN950005A1 - PROCEDURE TO OBTAIN THE COLOR VARIATION OF ROCKS BY MEANS OF HEAT TREATMENT. - Google Patents

Abstract

The present invention refers to an industrial process for obtaining the variation of the natural color of ornamental stones used for flooring, claddings, decorations, and rocks in general. The chromatic modification is obtained by the combined action of time and temperature, in the oven ventilated in an oxidizing environment.

Description

DESCRIPTION of the industrial invention entitled: PROCEDURE TO OBTAIN THE COLOR CHANGE OF ROCKS BY MEANS OF THERMAL TREATMENT,

SUMMARY

The present invention relates to an industrial process for obtaining the variation of the natural color of the ornamental stones used for flooring, cladding, decorations, and of rocks in general.

Said procedure has irreversible characteristics. lity, and causes the chromatic variation in the whole lithoid mass, both on the surface and in depth: the stone can be worked in times even after the treatment without the artificial coloring suffering from it or chromatic continuity occurring in the parts exposed during processing.

There are various types of rock that can profitably be subjected to the process of chromatic variation; currently excellent results are obtained in the treatment of rocks called "Quartzites" (Quartzite: monomineral metamorphic rock, that is composed almost exclusively of quartz granules; lithoid material easily split into thin slabs. It is an excellent material for cladding and flooring. ).

Currently, the stones are worked in the quarry color. Some users partially modify the color of the stones through contact treatments with chemical substances (liquid or gaseous): the treatment is only superficial and unstable over time. As already mentioned, the process of which the present description is instead aimed at obtaining the chromatic variation within the whole rock mass, and is irreversible. Colors are obtained that do not exist in non-freezing rocks. For example, yellow quartzite becomes salmon pink after treatment; gray quartzite becomes purplish color.

DESCRIPTION

The industrial process by which rocks change color is as follows:

The rocks are introduced in a ventilated oven, in an oxidizing environment. The temperature of the oven depends on the size of the rocks (usually the stones are reduced to such a size that they can be easily handled; and they are stacked on pallets. This however is not essential), and varies from 180 ° C to 450 ° C.

Below 180 ° C the chromatic transformation does not occur; above 450 ° C the stone regains its original color, calcifies with modification of the crystalline structure and becomes brittle. An optimal temperature has proved to be around 240 ° C.

The rocks remain in the oven for a variable time from 4 to 10 hours: also the permanence in the oven is a consequence of the size and thickness of the stones, as well as of the temperature.

Cooling is gradual, partly in the oven and partly in a thermally insulated environment (insulating bell). The insulating bell can be used, by means of heat recovery, for the preheating of the rocks not yet treated.

Claims (1)

CLAIMS 1 - Process for obtaining the chromatic variation of rocks by means of thermal treatment as described above. 2 - As claim no. 1), with treatment to be carried out using a ventilated oven. 3 - As rev. No. 1) and 2), with treatment to be carried out in an oxidizing environment. 4 - As rev. No. 1), 2) and 3), with the combined action of time and temperature. - As rev. No. 1), 2), 3) and 4), possibly using the preheating system of the rocks not yet treated. - As rev. No. 1), 2), 3), 4) and 5), using the gradual cooling system in the treatment. - As rev. No. 1), 2), 3), 4), 5) and 6), with the use (in the cooling of the treated rocks and in the preheating of the rocks to be treated) of an insulating bell.