AU2010317231B2 - Composition used to produce igneous rock crystal glass material, igneous rock crystal glass material and production method thereof - Google Patents

Abstract

A method for producing igneous rock crystal glass material comprises the following process steps: crushing ore, pre-treating crushed ore, mixing supplementary material, melting mixed material and preparing the finished product. Said ore is the igneous rock. Pre-treating crushed ore involves water-washing or acid-washing plus water-washing, in which the acid used in acid-washing is hydrochloric acid, nitric acid or sulfuric acid with the mass concentration of 1-50%. Stirring and dipping in acid is performed for 0.5-24 hours. Said supplementary material is at least one of SiO

Description

1 COMPOSITIONS USED TO PRODUCE IGNEOUS GLASS MATERIAL, IGNEOUS GLASS MATERIAL AND PRODUCTION METHOD THEREOF 5 Field of the invention The present invention relates to the technology of manufacturing mineral glass, of which the ore includes felsic, intermediate, mafic, and ultramafic igneous rocks. More specifically, the invention relates to the compositions used to produce igneous glass, 10 the compositions of the obtained igneous glass material and the processing method. Background art Igneous rock is consolidated magma, accounting for 95% of the earth crust. Magma devitrifies during cooling and turns into igneous rock, containing a majority of 15 devitrified crystalline phase and a minority of glass phase, which is called devitrified glass or glass-ceramic. When falling into water in particular case, magma consolidates before crystalline seeds grow. The obtained volcanic glass is called obsidian, or fire jade, or black crystal. Accordingly, the obtained mineral glass using this innovated method is called igneous crystal glass or simply igneous glass, to 20 distinguish from ordinary glass made by industry pure chemicals. Igneous rock is classified into felsic (silica content>65%), intermediate (silica content 52-65%), mafic (silica content 45-52%), and ultramafic (silica content<45%), with more than 700 species. Traditional secondary igneous products made by melting and casting method are basically basalt (a typical mafic igneous rock) glass-ceramic 25 (also called as casting stone or devitrified glass). In 1914, Francois Ribbe found that reheating the basalt cast to 800 oC for 0.5-1.5 hours, before the temperature of the melt dropped to 500oC, would generate numerous microcrystallines, which improved the toughness and strength of the basalt glass-ceramic casts (US1108007). In 1933, US1893382 further reported the 30 processing method for producing basalt glass-ceramic and later in 1956 Dr. Stooky introduced this technology to make glass-ceramic using devitrifiable ordinary glass (US2920971). In 1969, US3557575 proposed to melt basalt rock in oxidizing atmosphere and anneal in non-strong oxidizing atmosphere, which has been following by basalt glass-ceramic millers. 35 The melting and devitrifying temperatures of basalt range from 1350-1500oC CN1789187) and 760-1100 oC, respectively (Qibing Gu, et al., "Study on the 2 crystallizability of basalt melt", Fiber Glass, 2007(5): 6-10). Among the oxide compositions of basalt rock, the major part of crystalline seeds is Fe2O3. When Fe2O3/FeO>0.5, intensive devitrification occurs during cooling and reheating, which can always be achieved when exposing the basalt melt to air. Moreover, the oxidizing 5 atmosphere may be further enhanced by adding oxidants, such as NH4NO3 and MnO2 (Jinshu Chen, "Devitrified glass", Press of Chemical Industry, Beijing, 2006). Generally, the bending strength of basalt glass-ceramic is around 30-80MPa. The method making basalt glass-ceramic with high devitrification tendency has the following weaknesses: 10 1. High manufacturing cost: A typical basalt glass-ceramic manufacturing procedure comprises the following steps: adding NH4NO3 as the oxidant, keeping the cast at 65OoC for 4 hours, reheating at 880oC for 1 hour, then annealing to room temperature (Jinshu Chen, "Devitrified glass", Press of Chemical Industry, Beijing, 2006). The extra 5 hours' heating is costly and energy consuming. 15 2. Low yield ratio: The cast of glass-ceramic may be rejected due to over devitrification when slow cooling, or rejected due to broken when rapid cooling. It was reported that the yield ratio of glass-ceramic industry was below 60% (www.bmlink.com/news, Web of China Construction Materials, 2008). The melted basalt has extreme high tendency of devitrification and thermal expansion. Hence, the 20 yield ratio of basalt glass-ceramic cast is far lower than that of other glass-ceramic materials. The devitrified basalt cast is dull and rough due to the embedded crystallines and the application is largely limited to anti-erosion pipes. 3. Quality deterioration: Besides oxidants, the fluxing agents, such as limestone, sodium carbonate and fluorite, are added to promote further devitrification. These 25 fluxing agents reduce the viscosity and melting temperature, by breaking the molecular structure of silica, which definitely deteriorates the thermal stability, chemical stability and strength of final product. In addition, strong oxidizing atmosphere has been using to increase the value of Fe2O3/FeO for intensive devitrification. However, it is recognized that the smaller the Fe2O3/FeO value is, the 30 better the mechanical property is. The benefit of crystalline to mechanical property is offset by the increase of Fe2O3/FeO value (Jinshu Chen, "Devitrified glass", Press of Chemical Industry, Beijing, 2006; Ping Li and Zhi Ou, "Correctly understanding basalt fiber ", Fiber Glass,2008(3):35-41; US4009015,1977). 4. Limitations: The traditional processing method of basalt glass-ceramic 35 increases Fe2O3/FeO value by adopting strong oxidizing atmosphere and increases 3 the efficiency of devitrification by compromising the yield ratio, which limits further improvement of material performance and may be not directly applicable to these felsic and intermediate igneous rocks containing high proportion of anti-devitrification compositions. 5 The method of manufacturing glass-ceramic may improve the strength of ordinary devitrifiable glass, but it is not the case of basalt glass-ceramic as stated above. The benefit of devitrification in terms of improving mechanical property is offset by the surface flaw due to rapid cooling, local over devitrification due to slow cooling, the break of molecular structure due to flux agents, and high Fe2O3/FeO value due to 10 oxidizing atmosphere. "Glass-ceramic industry is facing its difficulties, such as surface pores, low yield ratio, limitation of varieties, and high operation costs (www.bmlink.com/news/ message/160393.html, Web of China Construction Materials, 2008)." The whole glass-ceramic market is diminishing in recent years and the basalt glass-ceramic 15 market is even worse, resulting from its low yield, high energy consumption, and peeling off of crytallines during machining. Summary of the invention Igneous rock is a natural glass-ceramic or devitrified glass, with a majority of 20 devitrified crystalline phase and a minority of glass phase. The melted igneous, the same as magma, naturally devitrifies during cooling, especially after adding oxidants and flux agents. This invention attempts to provide a method for manufacturing igneous glass, including anti-devitrification melting method, anti-devitrification auxiliary materials and other associated anti-devitrification techniques. The traditional 25 methods for making igneous glass-ceramic, which intend to increase devitrification since it has been regarded as inevitable, are completely eliminated. This invented method for making igneous glass comprises the following steps: ore pretreating, auxiliary agents mixing, melting and product forming, wherein the described igneous rock is grinded into particles with diameters 0.1-5 mm and are 30 pretreated by water-washing or acid-pickling followed by water-washing; the said acid can be hydrochloric, nitric acid or sulfuric with concentration 1-50%; the soaking and stirring time of acid-pickling is from 0.5 to 24 hours; wherein the said auxiliary materials are at least one of SiO2, A1203, MgO, B203, ZrO2, La2O3 and Y203, and the mass of the auxiliary materials is 1-30% of that of igneous rocks; wherein the 35 designed ambient temperature ranges from 50 oC above the melting temperature of igneous ore to 50 oC below the boiling temperature of igneous ore; the melting 4 atmosphere includes reducing, nitriding, vacuum or sealed atmosphere; wherein the said product forming involves in casting, molding, or rolling, or blow molding, or quenching in water followed by smashing into powder. The compositions used for making igneous glass are igneous rocks and 5 auxiliary materials, wherein the auxiliary materials are at least one of SiO2, A1203, MgO, B203, ZrO2, La2O3 and Y203, and the mass of the auxiliary materials is 1-30% of that of igneous rocks. The obtained igneous glass material comprises the following compositions: SiO2 45-90%, A1203 5-25%, Fe2O3 1-15%, FeO 1-15 %, MgO 1-15%, CaO 1-15%, 10 Na2O 1-15%, K20 1-15%, TiO2 0-5%, B203 0-5%, ZrO2 0-5%, La2O3 0-5% and Y203 0-5%. In contrast to the method making basalt glass-ceramic, this invention introduces a novel processing method, auxiliary agents, and associated approaches to avoid devitrification. Hence, the made glass can be cooled slowly without over devitrification 15 or broken. In addition, the oxidants and flux agents used for glass-ceramic have side effects to increase thermal expansion and weaken physical and chemical performances, whereas the anti-devitrification auxiliary materials all act to significantly improve the performance of final product. As a matter of fact, the bending strength of product obtained in Sample 1 is around twice as much as the commercial basalt 20 glass-ceramic. The obtained igneous glass has a gem appearance, excellent uniformity, thus machining property. In addition, the yield ratio, performances and energy consuming of igneous glass are far superior to these of basalt glass-ceramic. This invention may be distinguished from the method for basalt glass-ceramic in the following aspects: 1) igneous glass and basalt glass-ceramic are different 25 materials. Igneous glass has only glass phase and was certificated as a gem, namely black crystal or obsidian. Basalt glass-ceramic is a rock, containing both glass and devitrified crystalline phases; 2) the auxiliary agents for igneous glass are facilitated to avoid devitrification, whereas these for basalt glass-ceramic aim high devitrification, which leads to significant difference in compositions; 3) the method of this invention is 30 robust for all igneous rocks and the applicability is better than the method for basalt glass-ceramic; 4) igneous glass can slowly cool down to achieve 100% yield ratio, without over devitrification or broken, whereas the yield of basalt glass-ceramic is always a dilemma problem and the product may be rejected due to over devitrification when slow cooling, or rejected due to breakage when rapid cooling. 35 5 Brief description of the drawings The accompanying drawings are as follows: Figure 1 shows the flow chart of processing method for manufacturing igneous glass; 5 Figure 2 shows the continuous igneous fiber made by the modified intermediate igneous glass of Sample 1; Figure 3 shows the photo of the mafic igneous glass of Sample 2 (3a is a bracelet made by natural obsidian, 3b is an igneous glass plate); Figure 4 gives the photo of the felsic igneous glass powder made in Sample 3; 10 Figure 5 shows the report of X-RAY diffraction: the devitrification of the modified intermediate igneous glass made in Sample 1 is negligible; Figure 6 presents the curve of the thermal expansion coefficient against temperature (unit: 10-6/ ) for the igneous glass of Sample 1; Figure 7 illustrates the curves of dielectric constant E' and dielectric dissipation E" 15 for the igneous glass of Sample 1; Figure 8 illustrates the curves of magnetic conductivity p' and magnetic dissipation p" for the igneous glass of Sample 1. DETAILED DESCRIPTION OF THE INVENTION 20 The proposed sizes of the smashed rock are between 0.1-5 mm. Large igneous particles may result in lithic defects when melted incompletely. In addition, the auxiliary materials are normally in powder form, which cannot be well mixed with large igneous particles. Extreme fine igneous powder is likely to be blown into air or clotting. The proposed size for crucible melting is above 0.1mm, for tank furnace melting is 25 above 0.25mm. It is noted that the quarry industry regards the igneous pebbles less than 5mm as waste. The proposed particle size range 0.1-5 mm of this invention is cost effective. The raw igneous particles are pretreated by water-washing or acid-pickling followed by water-washing, wherein the concentration of pickling acid ranges 1-50% 30 and the acid can be hydrochloric, nitric acid or sulfuric; the soaking and stirring time of acid-pickling is from 0.5 to 24 hours. The traditional pretreatments of basalt secondary processing are water-washing or alkali-washing, in which the alkali-washing may lead to higher devitrification (CN101263090, 2008). In this invention, the acid-pickling is 6 applied to reduce the content of impurity, volatile substance, crystalline seeds, and alkali oxides, in order to reduce devitrification, increase melt viscosity, enhance thermal stability and improve the overall performances of final product. The auxiliary materials used in this invention include at least one of SiO2, A1203, 5 MgO, B203, ZrO2, La2O3 and Y203 and the mass of described auxiliary materials is 1- 30% of that of igneous rock. It is known that A1203, MgO and ZnO reconnect the broken molecular chains of silica-oxygen tetrahedron to reduce devitrification; A1203 ,B203 and Ga2O3 are powerful to stop the accumulation of ions with intensive electric field outside the network to reduce devitrification; SiO2, A1203, ZrO2, B203, 10 MgO and ZnO increase the thermal stability to reduce breakage; La2O3, TiO2 and Y203 improve the elastic modulus and toughness; ZrO2, SnO2 and La2O3 are useful against alkali corrosion; ZrO2, A1203 and ZnO are commonly used to resist acid corrosion. It is noted that ZrO2 is powerful for improving chemical, mechanical and thermal performances, but ZrO2 may result in devitrification if its content in the melt 15 exceeds 5%. The designed ambient temperature of this invention ranges from 50 oC above the melting temperature of igneous ore to 50 oC below the boiling temperature of igneous ore. Igneous is a thermal insulation material and hard to melt below the proposed lower temperature limit. When the ambient temperature of the furnace exceeds the 20 proposed upper limit, the igneous melt may spill. In addition, higher temperature results in lower melt viscosity, thus severer damage to melting facility. The atmosphere of this invention is non-strong oxidizing atmosphere, including reducing, nitriding, vacuum or sealed atmospheres. The reducing atmosphere is normally achieved by blowing in hydrogen, carbon monoxide or/and inert gases; or 25 adding reducing agents, including the powders of carbon, carbon carbohydrates, potassium tartrate, tin and antimony; or/and using graphite crucible, or/and using graphite electrodes. Reducing atmosphere turns devitrifiable Fe2O3 into anti-devitrification FeO and lowers the Fe2O3/ FeO value to improve mechanical performance of final product. 30 The nitriding atmosphere is achieved by blowing in nitrogen for 2-16 hours, or/and adding in 1-3% of nitrides, selected from at least one of the Si3N4, AIN and Li3N compounds (demonstrated in Sample 3). After the oxygen atoms of silica are replaced by the nitrogen, the resulting silicon oxynitride glass has far better elastic modulus, anti-erosion and anti-wear properties. However, the nitriding atmosphere is 35 not applicable for basalt glass-ceramic manufacturing, since such an atmosphere may 7 obstruct devitrification and increase the difficulty of forming basalt fiber. Vacuum and sealed atmospheres do not raise Fe2O3/FeO value. When Fe2O3 contain is sufficiently low, or/and other anti-devitrification techniques are adopted, or/and quenching is applied to make glass powder, vacuum and sealed atmospheres 5 are applicable. For instance, igneous ore is melted in vacuumed or sealed graphite crucible. The final product can be formed by molding, or casting, or rolling, or mold blowing, or quenching in cold water followed by smashing into powder, after the igneous melt is homogenized and refined. 10 The method of this invention is robust. The igneous melt does not devitrify, so can be slow cooled to avoid broken and achieve a high yield ratio. This is helpful to maintain a relative stable product quality when the compositions of raw materials fluctuate all the time. The igneous glass has more varieties than basalt glass-ceramic. The continuous 15 fiber with dark grey color shown in Figure 2 is made by intermediate igneous glass of Sample 1. The igneous glass plate has the same appearance as obsidian and fire jade (Figure 3), whereas the basalt glass-ceramic is dull and rough with a number of surface pores. The felsic igneous glass powder is shown in Figure 4. In summary, the igneous resource is better utilized by this invention than the traditional glass-ceramic 20 method. The implementing samples are presented as follows. It should be noted that the implementing samples are further interpretation of the developed method and do not limit the claims of this invention. SAMPLES OF THE METHOD EMBODIMENT 25 Sample 1 The igneous glass of Sample 1 was made by an intermediate igneous (andesite basalt) and the mechanical, thermal and electromagnetic properties were examined by 30 the related organizations. Table 1. The andesite basalt (intermediate igneous) compositions with content >1%. Comp SiO 2 A1 2 0 3 MgO CaO Na 2 O K 2 0 TiO 2 Fe 2

O

3 Fe 2

O

3 / osition +FeO FeO wt% 52.06 14.75 6.55 6.77 2.32 1.38 1.08 11.62 1.13 The raw andesite basalt ore was smashed to particles with sizes smaller than 5 8 mm. The particles were immersed in 20% sulfuric acid solvent for 0.5 hour, then water-washed for 0.5 hour. The treated materials were mixed with SiO2, ZrO2 and A1203 at the mass ratios of 1%, 2% and 3%, progressively. The mixture was melted in a sealed furnace at the ambient temperature 1500oC. After one hour's refining, the 5 temperature of igneous melt was reduced to 1 OOOoC and the melt was casted into an iron mold that was preheated to 600 oC. No surface check and devitrification were found in the products (Figure 5). There were plenty of crystalline seeds Fe2O3 in the raw andesite basalt, and the Fe2O3/FeO value was 1.13, far larger than the critical value 0.5 for significant 10 devitrification (Table 1). However, the devitrification of the obtained mineral glass was negligible (Figure 5), after acid-pickling and adding SiO2, ZrO2 and A1203, which indicates that the method proposed in this invention is feasible and practical. Table 2. The mechanical properties of the andesite basalt glass. Bending Elastic Shear Poisson's Fracture Vickers Mohs strength modulus modulus ratio toughness hardness hardness MPa GPa GPa MPa m 1 2 GPa 1-10 131.19 93.17 37.16 0.253 1.01 6.57 7-8 15 The bending strength of basalt glass-ceramic is around 67MPa and far weaker than the tensile and compression strengths, which is thus used as the key mechanical feature of basalt glass-ceramic (G. Xiao, "Applying basalt glass-ceramic to the slag runner of blast furnace", Shandong metallurgy, 25(6):68-69,2003; Z. Xu, "Casting 20 stone manufacturing", Today's technology, 1990(3):13,1990). The bending strength of the obtained andesite basalt glass was 131.19 MPa, which is around twice as much as the average bending strength of basalt glass-ceramic. Thermal expansion coefficient is the major index of thermal stability. The thermal expansion coefficients of the obtained igneous glass were 6.0688, 6.6979, 7.1705 and 25 7.4581 (10-6/ , Figure 6) at temperatures 100, 300, 500 and 700oC, which showed that the thermal expansion coefficient went up with the ambient temperature. The corresponding regression equation is given as below: Thermal expansion coefficient 1 0- 6 /C=0.0023T+5.9207 (R 2 =0.9736,TE 100-700'C) 30 Table 3. The electrical properties of the obtained andesite basalt glass. Electrical volume Dielectric Dielectric Dielectric Dielectric resistivity dissipation dissipation constant constant tangent tangent 1KHz 1 MHz 1KHz 1MHz 9 0.4-3.8x10 Q.cm 0.041 0.015 10.94-11.96 10.85 A material with electrical volume resistivity larger than 109Q.cm is defined as electrical insulation material. The electrical volume resistivities of the obtained andesite basalt glass were reported falling in the range of 0.4 - 3.8x1 01 2Q.cm, which 5 indicates that the andesite basalt glass is an excellent insulation material (Table 3). It is called dielectric dissipation material when the corresponding dielectric dissipation tangent is larger than 0.01. The data shown in Table 3 indicate that the obtained andesite basalt glass is a dielectric dissipation material. Besides electrical insulation, the obtained andesite basalt glass is also an 10 excellent thermal insulation material and the examined thermal conductivity was 0.033 W.M-1.K-1. In addition, the sound absorption of igneous products is normally between 90-99%. Therefore, igneous glass is both sonar and infrared stealthy. It was found that the dielectric constant and dissipation of the obtained igneous glass moved down with the increase of electrical frequency, whereas the magnetic 15 conductivity and dissipation of the obtained igneous glass went up with the increase of electrical frequency (Figures 7-8). The results reveal that the obtained andesite basalt glass is not only infrared stealthy and sonar stealthy, but also radar stealthy. The regression models of dielectric constant, dielectric dissipation, magnetic conductivity and magnetic dissipation are given as follows: 20 Dielectric constant E'= -0.0247(GHz)2+0.1431 (GHz)+7.6958 (R2=0.9987, GHzE 8.2-12.4); Dielectric dissipation E"=-0.01 33(GHz)2+0.2269(GHz)-0.5974 (R2=0.9571, GHzE 8.2-12.4); Magnetic conductivity p'=0.0089(GHz)2-0.1341 (GHz)+1.3605 25 (R2=0.9985, GHzE 8.2-12.4); Magnetic dissipation p"= 0.0026(GHz)2-0.0481 (GHz)+0.2388 (R2=0.9692, GHzE-8.2-12.4). Sample 2 30 Sample 2 made a black crystal glass using basalt, a mafic igneous rock. The sample was made to estimate the lowest processing cost and the lower limits of mechanical properties for the igneous glass with low framework composition SiO2. The obtained basalt glass was proposed to make black crystal art crafts, namely 10 molding or carving into ornaments. Table 4. The basalt (mafic igneous) rock compositions with content >1%. Composition SiO 2 A1 2 0 3 MgO CaO Na 2 O K 2 0 Fe 2

O

3 +FeO wt% 49.16 14.04 7.31 6.68 3.32 2.17 7.81 5 The raw basalt particles described in Table 4 were the waste of a quarry, with sizes less than 5 mm, which were pretreated in 20% sulfuric solvent for 8 hours and washed in water for 0.5 hour. The basalt particles were melted at temperature 145OoC in a corundum crucible. After refining, the melt was casted to an iron mold that preheated to 600 oC. A basalt glass plate was made with 10mm in thickness (Figure 10 3b). The plate was annealed in oven for 8 hours and the upper limit of the annealing curve was 840 oC. Table 5. The measured mechanical properties of the obtained basalt glass. Bending strength Elastic modulus Fracture toughness Mohs hardness MPa GPa MPam 1-10 66.49 93.60 1.04 6-7 15 Sample 3 The raw material of Sample 3 was pearlite (felsic igneous) powder, which was mixed with 1% of ZrO2 and 1% of La2O3, to enhance the strength and reduce thermal expansion. The mixture was melted in a graphite crucible at 1800 oC in a nitriding atmosphere (adding 1% of Si3N4 and blowing in nitrogen for 10 hours). The melt was 20 poured into circulating cooling water to break into pieces, then grinded into powder. The activity indices for compositing with cement were 38% on the 7th day and 53% on the 28th day, which reveals that the pearlite glass power and fiber reinforced cement has excellent interfacial fastness (Table 7). 25 Table 6. The pearlite (felsic igneous) rock compositions with content >1%. Composition SiO 2 A1 2 0 3 CaO Na 2 O K 2 0 Fe 2

O

3 +FeO wt% 74.75 13.49 1.21 3.83 4.14 1.71 Table 7. The activity indices of the perlite glass as a cement reinforcement. Activity index on the 7 th day Activity index on the 2 8 th day 38% 53% Sample 4 30 The compositions of the raw basalt waste, with sizes less than 5mm, are given in Table 8. The ore was soaked and stirred in 20% sulfuric solvent for 2 hours 11 and washed in water for 0.5 hour. The air-dried basalt waste was mixed with 1% of carbon powder and melted at ambient temperature 1450o0C. The obtained basalt glass prism bars were buried inside expansion pearlite powder for 7 days to release the internal stress. The Mohs hardness of the obtained basalt glass was 6.5, which is 5 much higher than the 5.5 Mohs hardness of natural obsidian (or black crystal). Table 8. The basalt mafic igneous) rock compositions with content >1%. Composition SiO 2 A1 2 0 3 MgO CaO Na 2 O K 2 0 Fe 2

O

3 +FeO wt% 43.57 12.98 6.36 6.76 2.45 1.02 11.00 Sample 5 10 10kg raw basal waste was soaked and stirred in 20% sulfuric solvent for 24 hours and washed in water for 0.5 hour. Auxiliary materials are adopted to improve the elastic modulus of the modified basalt glass and the amount of the added SiO 2 , ZrO 2 ,

Y

2 0 3 and MgO are 3%, 1%, 0.8% and 1% of the mass of basalt ore, respectively. The mixture was melted and refined at 1500 C. The elastic modulus of the made basalt 15 fiberglass was 98.21 GPa and the compositions of the basalt glass are shown in Table 9. Table 9. The major compositions of the obtained basalt (mafic igneous) fiberglass. ZrO 2

Y

2 0 3 SiO 2 A1 2 0 3 MgO CaO Na 2 O K 2 0 Fe 2

O

3 +FeO TiO 2 0.93 0.75 51.02 12.38 9.42 6.56 2.45 1.02 11.01 2.21 20

Claims (12)

1. A composition used to manufacture igneous glass having negligible devitrification, wherein the composition consists of igneous rocks and auxiliary materials, the said 5 igneous rocks include felsic, intermediate, mafic and ultramafic igneous; the said auxiliary materials include at least one of SiO 2 , A1 2 0 3 , MgO, B 2 0 3 , Zr02, La 2 0, and Y 2 0 3 ,and the mass of described auxiliary materials is 1- 30% of that of igneous rocks.

2. A composition according to Claim 1 for manufacturing igneous glass having negligible devitrification, wherein the composition consists of intermediate igneous 10 rock and auxiliary materials consisting of SiO2, A1203 and ZrO2, in which the contents of SiO2, A1203 and ZrO2 are 1%, 3% and 2% of the mass of igneous rock, progressively.

3. A composition according to Claim 1 for manufacturing igneous glass having negligible devitrification, wherein the composition consists of felsic igneous rock and 15 auxiliary materials La2O3 and ZrO2, in which the contents of La2O3 and ZrO2 are both 1% of the mass of igneous rock, respectively.

4. A composition according to Claim 1 for manufacturing igneous glass having negligible devitrification, wherein the composition consists of mafic igneous rock and auxiliary materials SiO2, Y203, MgO and ZrO2, in which the contents of SiO2, Y203, 20 MgO and ZrO2 are 3%, 0.8%, 1% and 1% of the mass of igneous rock, progressively.

5. A method for manufacturing igneous glass having negligible devitrification, including a composition according to any one of claims 1 to 4, the method including the following steps, including in pretreatment of igneous ore, melting and product formation, wherein the pretreatment comprises water-washing, or acid-pickling 25 followed by water-washing; the designed ambient temperature in the melting step ranges from 50 oC above the melting temperature of igneous ore to 50 oC below the boiling temperature of igneous ore; the melting atmosphere excludes strong oxidizing; the final product forming involves casting, or molding, or rolling, or mold blowing, or quenching in water followed by smashing into powder. 13

6. A method of manufacturing igneous glass having negligible devitrification according to Claim 5, wherein the concentration of pickling acid ranges 1-50% and the acid is hydrochloric, nitric acid or sulfuric; the soaking and stirring time of acid-pickling is from 0.5 to 24 hours. 5

7. A method of manufacturing igneous glass having negligible devitrification according to Claim 5, wherein the melting atmosphere includes reducing, nitriding, vacuum or sealed atmosphere.

8. A method of manufacturing igneous glass having negligible devitrification according to Claim 7, wherein the reducing atmosphere is achieved by blowing 10 carbon monoxide gas, or/and adding 1-3% of carbonized powder, or/and using graphite crucible, or/and using graphite electrodes.

9. A method of manufacturing igneous glass having negligible devitrification according to Claim 7, wherein the nitriding atmosphere is achieved by blowing in nitrogen for 2-16 hours, or/and adding in 1-3% of at least one of nitrides selected from 15 Si3N4, AIN and Li3N compounds.

10. A method of manufacturing igneous glass having negligible devitrification according to any one of Claim 5-9, wherein the igneous rocks are grinded into the sizes with diameters 0.1-5mm.

11. A method of manufacturing igneous glass having negligible devitrification 20 according to any one of Claim 5-10, wherein the pre-treated igneous particles are well mixed with auxiliary materials, the auxiliary materials comprise at least one of SiO2, A1203, MgO, B203, ZrO2, La2O3 and Y203 and the added auxiliary materials is 1-30% of the igneous ore in terms of mass.

12. An igneous glass material having negligible devitrification according to Claim 5 25 comprises: SiO2 45-90%, A1203 5-25%, Fe2O3 1-15%, FeO 1-15%, MgO 1-15%, CaO 1-15%, Na2O 1-15%, K20 1-15%, TiO2 0-5%, B203 0-5%, ZrO2 0-5%, La2O3 0-5% and Y203 0-5% by weight