Patent Application
20190256422
The present invention relates to the manufacturing and use of an artificial, inorganic, porous, igneous silicate based rock material, made from a process of sintering a mixture of quartz sand and minerals by an extrusive or intrusive process, and further a method of processing the igneous silicate based rock material into other commercial products.
Due to increased demand for clean recycled glass cullet to be used in traditional glass production the amount of recycled glass available for the making of other high-quality foamed glass products is limited. In addition, the cost of sorting the collected glass and the amount of CO2 created from transport of the recycled glass material are high.
Due to increased demand for pumice stones from open quarries to be used as media filter in water treatment or pre-treatment of salt water or brackish water before reverse osmosis, the negative environmental impact is huge, and at the same time the quality of the extracted pumice stone material is not as consistent and high as before and sometimes it needs to be refined before use.
In some instances, the use of materials made from recycled glass may cause risk of contaminating the ground water when used in infrastructure project below ground, or limit its use as infill in concrete due to its high alkali reactivity, or limit its use as a clean and inert media filter in fresh water treatment.
The present invention provides a pure and inert raw material with low alkali reactivity to be used as raw material when making infill in concrete, a material without any content of antimony, arsenic or other substances that causes any harm to the ground water if used as raw material for lightweight aggregate, a clean and stable material that can be used as media filter in water treatment and pre-treatment before reverse osmosis, and as growth media in hydroculture without any harm for plants, animals or humans.
This material can replace partially or in full the use of recycled glass in making of cellular glass products, the use of expanded clay as infill in concrete, and the use of pumice stones, perlite, quartz sand, glass sand and other material as media filter in fresh water treatment, pre-treatment before desalination, koi ponds, and it can be used as a growth media in hydroculture.
The porous structure with open microcells on the surface and also throughout the material, makes it very well suited to be crushed down and still keep its porosity and large surface area.
The present invention relates to a method of making a porous silicate based rock material with similar properties as an igneous silicate based rock without being naturally occurring.
The igneous rock material can either be made by an extrusive sintering process at atmospheric pressure or by an intrusive sintering process under positive pressure.
This material consists of a mixture of quartz sand and different minerals heated up to a maximum temperature in the range from 960° C. to 1200° C., and atmospheric pressure or at a positive pressure between 0.01 bar and 3.0 bar, for the chemical reactions to take place and for the mixture to reach an elastic state and at a viscosity where the formed gasses are dissolved into the molten material without entering into a plastic state.
The positive pressure under an intrusive process can be achieved either by calculating the height of the furnace to use the weight of the mineral mixture to build up pressure, or to place the furnace inside a pressure chamber with the desired pressure.
The desired cell size of the igneous rock material will depend on the size of the particles of the foaming agent, the viscosity of the molten mixture, the positive pressure on the molten mixture when the mixture has reached its maximum temperature, and the process time at maximum temperature.
The main ingredient is quartz sand with a silica content of more than 70%. Then Sodium oxide is added to lower the melting point of the quartz, and Calcium oxide as stabilizer, for not making the igneous rock water soluble. If the quartz sand does not contain any aluminum oxide, a smaller amount can be added to the mixture to increase strength after the ceramic particles have been fused together.
The maximum temperature given by the viscosity of the molten material during its elastic state, and the positive pressure used, should be optimized so that the formed gas bubbles do not raise in the molten mixture but is trapped inside, forming an almost uniform cell structure before entering out of the bottom of the furnace to be cooled down to ambient temperature for further processing.
By trapping the CO2 gas created during the elastic state into the molten rock material, the amount of CO2 released to the atmosphere is significantly lower than in traditional glass production where almost all CO2 is removed during the refining of the glass at temperatures locally up to 1675° C.
Chemical reaction when heated (based on quartz sand with 99.9% SiO2):
Na2CO3+CaCO3+6SiO2=Na2O.CaO.6SiO2+2CO2
When using quartz sand with a lower SiO2 content, the chemical composition can be as follows:
An example of chemical composition after reaction:
The process gives a porous igneous rock with micro cells mainly based on CO2 bubbles made at a temperature where the given viscosity of the molten material doesn't allow the formed gas bubbles (seeds and blisters) to escape before it has been cooled down to a temperature where it reaches a solid state.
By use of a furnace, the mixture is heated to a temperature between 960° C. and 1200° C. to sinter the minerals without reaching a plastic state, to create bubbles from the chemical reaction that are taking place during its elastic state and to allow the bubbles to dissolve into the molten material, but not raise to the surface and form blisters. Changes in temperature and pressure will both influence the production time and also the amount of gasses dissolving into the molten material. The higher the viscosity, and higher the pressure, the higher the proportion of the released CO2 gasses becomes dissolved in the molten material over a fixed time. Different fraction size of the quartz sand and minerals will change the reaction time, and the fraction size should preferably not exceed 4 mm.
According to one aspect, the making of the product takes place through an extrusive process in a horizontal melting furnace under atmospheric pressure, or according to another aspect through an intrusive process by the use of a vertical furnace, or by putting the furnace inside a pressure chamber with a positive pressure in the range of 0.01-3 bar pressure above atmospheric pressure. The positive pressure in combination with the given viscosity of the molten material after the mixture has reached its elastic state will create a more uniform cell size distribution than in a horizontal furnace with a pressure below 0.01 bar pressure. Changes in pressure will change the size of the gas bubbles. Increased pressure will make the cell structure more homogenous and the cells smaller, less pressure will allow the bubbles to grow and pair up with other bubbles to form blisters over time. This effect will increase with increased temperature. The process should be optimized so as to minimize the pairing of bubbles and to create as uniform cell structure as possible, this to increase the quality of the material before further processing.
According to another aspect, the movement of the vertical oriented downward melting process should be faster than the rising of the bubbles created in the molten mixture. This to allow all bubbles created to stay inside the molten mixture and to create an igneous rock with as many cells as possible, and as low density as possible, when extruded out of the bottom of the furnace and before cooling.
According to another aspect and to be able to create a filtration media with particle size from 0.3 mm to 4.0 mm with low density and large surface area, the positive pressure when making a porous artificial igneous rock through an intrusive process is preferably adjusted so that the cell size decreases, and the mineral filter keeps its porosity and large surface even after crushing down to the desired size.
According to another aspect, an aluminum oxide (Al2O3) content of more than 2%, but no more than 10% in the quarts sand, will increase the strength of the cell walls and increase the melting point of the artificial igneous rock. If the quarts sand does not contain alumina, this can be added as part of the melting process, based on the specific end use of the artificial igneous rock material.
The invention will now be described with reference to the attached figures, wherein:
According to one aspect of the invention, a method for production of an artificial igneous rock, method is described in detail as follows:
65-84% by weight of Quartz sand with high SiO2 content is mixed with 8-20% by weight of Sodium oxide (Na2Co3), 8-15% by weight of Calcium oxide (CaCo3), and 2-10% by weight of Aluminum oxide (Al2O3) and heated up to a temperature in the range from 960° C. to 1200° C. The mixture is heated over the course of from 30 to 180 minutes, preferably over the course of 60 to 120 minutes, most preferably over the course of approximately 90 minutes. For lowering of the melting temperature, a portion of ready-made synthetic igneous rock milled down to fraction size below 1 mm may be added (10-40% by weight).
Example of production of igneous rock by an extrusive process under atmospheric pressure:
75% Quarts sand (including 7.5% Aluminum oxide)+15% Sodium oxide+10% Calcium oxide Batch of 2 kg, density 1.6 kg/l.
Height of mixture: 100 mm
Positive pressure: 0.016 bar at the bottom of mixture Heating from 20° C. to 1050° C. over 60 minutes
Hold at Tmax (maximum temperature) 30-90 min (depended upon the grain size), in this example 60 min with a grain size <0.8 mm
Then temperature is reduced to ambient temperature in a controlled temperature zone to reduce stress in the artificial rock.
The temperature is lowered before the molten mixture has reached a plastic state and just before any significant amount (preferably zero) gas bubbles start to pair up and burst through the surface of the melt. This can be observed as large craters on top of the surface of the melt.
The process time will depend on the amount of Sodium oxide in the blend and the maximum temperature used. A higher temperature and/or higher content of Sodium oxide gives a shorter process time.
In
The blend consists of 75% Silicon dioxide, 15% Sodium oxide and 10% Calcium oxide. Heated up in a furnace to a maximum temperature of 1050° C. and kept at maximum for 60 minutes before cooled down to room temperature, for further processing.
According to another aspect of the invention, a method for crushing the artificial igneous rock into sand for further use as filtration media for water treatment is possible.
An Example of Usage:
As shown in
If filtration media with small particle size and large surface area is needed, the igneous rock can be made by an intrusive process under positive pressure (preferably from 0.01-3 bar) to create a smaller cell structure, preferable with a cell size down to 0.01 mm. According to one aspect, this can be achieved by performing the process under positive pressure in a pressure chamber. According to another aspect, illustrated in
According to another aspect of the invention, a method for lowering the density of the filtration media is provided. By milling the igneous rock down to a fraction size below 700 micron, then adding 0.5-5% of a foaming agent such as SiC, MnO2, AlN or a combination of them, then heating up the mixture to a temperature from 820° C. to 1000° C., to create a foamed product with micro cells, then cool down to ambient temperature, then crush the foamed artificial igneous rock into the desired fraction sizes as shown in
Fraction sizes used for filtration media can be in the range:
0.3-0.6 mm,
0.8-1.6 mm,
1.8-2.5 mm,
2.5-4.0 mm,
Other ranges can be used dependent upon the end user filtration equipment and need.
Absolute particle density for the filtration media can range from 1.05 kg/l to 1.8 kg/l.
According to another aspect of the invention, a method of replacing recycled glass as the main raw material for production of cellular glass by methods known in the art is shown in
An Example of Usage:
A powder as shown in
Some characteristics of the cellular rock product:
Block density: 300-800 g/l
Thermal heat capacity: 0.050-0.090 W/mK
Compression strength: >1.5 MPa
Average cell size: 1 mm
Another Example of Usage:
An artificial igneous rock powder 0-100 micron as shown in
Some characteristics of the casted mineral foam product:
Block density: 400-600 g/l.
Compression strength: >7.5 MPa
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/077766 | 10/30/2017 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62481710 | Apr 2017 | US | |
| 62414817 | Oct 2016 | US |
