CN1147490A

CN1147490A - Method of processing white and grey granite into red granite

Info

Publication number: CN1147490A
Application number: CN 95114218
Authority: CN
Inventors: 黎兆安
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-10-10
Filing date: 1995-10-10
Publication date: 1997-04-16

Abstract

Natural white and grey granite plate after low-temp dried is first placed into sealed high-pressure container filled with ferric nitrate solution, where it is exerted with 3-6 MPa pressure for 1-2 hr, and then heated in heating tank at 100-200 deg.C for 1-3 hr. Under the high pressure, ferric nitrate solution is infiltrated into micropores of granite and the decomposed ferric oxide makes it red. The red granite is stable chemically and colourfast.

Description

Method for processing natural white and gray granite into red granite

The invention relates to a rock color-changing treatment process, in particular to a method for treating natural white and gray granites into red granites, which is suitable for the building material decoration industry.

At present, the gray variety of the natural granite plates for architectural decoration is many, and the natural granite plates with red basic tone are most popular among people. However, the storage capacity of red granite in nature is very limited, the variety is monotonous, and the requirement of modern architectural decoration on diversification cannot be met, and the defects that the natural red granite decorative plate has poor color uniformity and certain color difference, and must be selected and matched in high-grade architectural decoration are more and more cause that the price of the natural red granite decorative plate is high. The natural white and gray granite decorative plate is not gorgeous enough and lacks elegant quality, so the decorative plate is multipurpose in low-grade building decoration engineering. Because the natural white and gray granites have large storage amount and diversified patterns, how to change the natural white and gray granites into red fully meets the market demand is a subject which people hope to solve urgently. The Chinese patent gazette discloses a surface hyperchromic square-shaped dye (CN1074402A) of a red black granite stone plate, a preparation method of a colorant of a marble granite section and application thereof (CN 101636A). These methods, which turn stone slabs red by immersing the stone slabs in a coloring agent and applying the coloring agent to the surface of the stone slabs, have disadvantages of long processing time and discoloration.

The invention aims to provide a method for processing natural white and gray granites into red granites, which has the advantages of short processing time, low cost, uniform color and no fading, aiming at the problems in the prior art.

The task of the invention is realized in the following way: the method comprises the steps of firstly drying natural white and gray granite plates at low temperature, and is characterized by being placed into a high-pressure container, fully filling ferric nitrate solution, sealing, applying pressure of 3-6 MPa into the high-pressure container, maintaining the pressure for 1-2 hours, and finally taking out the granite plates and placing the granite plates into a heat preservation box at 100-200 ℃ for heat preservation for 1-3 hours.

The principle of the present invention is such; the granite is very compact in appearance, but a microscope shows that countless micropores exist in the granite, which is generated by a granite forming mechanism, an iron nitrate solution can permeate into the micropores through pressurization, and the decomposition reaction of the iron nitrate can be generated through heat preservation treatment at 100-200 ℃:

the gaseous substances after the reaction are discharged outside the stone plate, while the red Fe₂O₃The stone remains in the micro-holes of the stone plate, so that the stone plate turns red.

Compared with the prior art, the invention has the following advantages:

1. simple process, easy operation, short processing time and low processing cost.

2. The chemical property of the product is stable, the product is insoluble in water and is not oxidized, the color is uniform, and the problem of fading does not exist.

The method aims to remove moisture and impurities in micropores of the natural granite slab before the bleeding treatment so as to obtain a better bleeding treatment effect, and generally the drying temperature of 50-60 ℃ is more suitable. Because granite is compact and has small micropores, the osmotic pressure of ferric nitrate liquid is not less than 3NPa, otherwise, the ferric nitrate liquid is difficult to infiltrate into the micropores, the osmotic depth is influenced, and the osmotic time is increased, but when the osmotic pressure is more than 6MPa, the action is not obvious, the pressure-resistant requirement of a treatment container is also improved, and the investment of capital is relatively increased. Because the standard thickness of the granite plate is 20mm, when the pressure is applied for 1-2 hours, the ferric nitrate is permeated into the granite plate, the specific selection is more suitable for a plurality of hours, the density of the stone is generally determined, the loose structure can be used for 1 hour, and the compact structure needs 2 hours. As for the depth of the slate red, different concentrations of ferric nitrate solutions can be selected to achieve.

Before the plate color-bleeding treatment is carried out on a large scale, the process parameters which can meet the requirements of customers can be determined through tests.

Example (b): putting a white granite plate with the thickness of 20 mm into a drying room with the temperature of 60 ℃ for drying, then putting the plate into a high-pressure container, filling the high-pressure container with ferric nitrate solution, sealing, starting a high-pressure hydraulic pump to apply the pressure of 3MPa to the ferric nitrate solution in the high-pressure container, maintaining the pressure for 2 hours, and finally putting the high-pressure container into an incubator with the temperature of 200 ℃ for heat preservation for 2 hours. The granite board with uniform red inside and outside is obtained by the treatment.

Example 2, a gray granite slab having a thickness of 20 mm was dried in a drying room at 60 ℃, then the slab was placed in a high-pressure vessel, and then the high-pressure vessel was filled with a ferric nitrate solution, after sealing, a high-pressure hydraulic pump was started to apply a pressure of 6MPa to the ferric nitrate solution in the high-pressure vessel, and the pressure was maintained for 1 hour, and finally the slab was placed in an incubator at 100 ℃ and kept for 3 hours. The granite board with uniform red inside and outside is obtained by the treatment.

Claims

1. A method for processing natural white and gray granite into red granite comprises the steps of drying a natural white and gray granite plate at a low temperature, and is characterized in that the natural white and gray granite plate is placed into a high-pressure container, is filled with ferric nitrate solution, is sealed, applies pressure of 3-6 MPa to the high-pressure container, maintains the pressure for 1-2 hours, and is taken out and placed into a heat preservation box at the temperature of 100-200 ℃ for heat preservation for 1-3 hours.