Using tailings to melt glass

I. Overview

Ionization is a homogeneous, homogeneous solid material of amorphous amorphous material obtained by subcooling the melt. It has good mechanical properties: compressive strength of 5,000 to 20,000 kg / cm ^2, antiallergic strength of not less than 450 kg / cm ^2, density 2500 kg / m ^3, the thermal conductivity between 0.6 and 0.75, a hardness of 5 degrees the above. At the same time, glass is a material with high chemical stability. Besides hydrofluoric acid, it has good stability to other acids. Although alkali solution or even pure water can damage the surface of glass, its effect is not strong and the progress is extremely high. slow.

Glass is widely used. In addition to industrial technology, glass is generally required for buildings, and many household utensils can also be made of glass.

Glass is a complex of potassium silicate, sodium, calcium, aluminum, etc., its chemical composition is mainly: silica (SiO ₂ ), followed by: sodium oxide (Na ₂ O), potassium oxide (K ₂ O), oxidation calcium (CaO), magnesium oxide (MgO) and aluminum oxide (Al ₂ O ₃₎ and the like.

The main raw material for producing glass is quartz sand or quartz sand; followed by: feldspar, limestone, dolomite, fluorite, soda ash, Glauber's salt, boric acid, barite, potash, red lead, zinc white and the like. In addition to the above-mentioned raw materials, tailings mainly composed of quartz or feldspar are used at home and abroad as the main raw material for adding or adding ingredients for the experimental research of the molten glass, and some have been used for production.

In order to facilitate the selection of tailings close to the glass raw materials as the main raw material of the glass or to add ingredients to melt the glass, the following describes the quality requirements of the main raw materials used in the production of glass:

(a) quartz or quartz sandstone

The quality requirements for quartz or quartz sandstone are shown in Table 1.

Table 1 Quality requirements

NOTE: iron oxide (Fe ₂ O _3), chromium oxide (Cr ₂ O _3), titanium oxide (TiO ₂₎ are both harmful impurity components, which bring the glass color.

Quartz sand and quartz sandstone have particle sizes between 0.1 and 0.75 mm. Preferably, 70% to 80% is in the range of 0.1 to 0.5 mm.

(2) Adding materials

1. Dolomite

First grade: MgO>20%; Fe ₂ O ₃ <0.1%.

Secondary product: MgO>19%; Fe ₂ O ₃ <0.2%.

Particle size: 0.75 ~ 1.0 mm.

2, limestone

First grade: CaO>54%; Fe ₂ O ₃ <0.15%.

First grade: CaO>47%; Fe ₂ O ₃ <0.2%.

The glass is suitable for dolomitic limestone and limestone with little hardness. The particles are larger than 0.75 to 1.0 mm.

3, feldspar

Al ₂ O ₃ >18%; Fe ₂ O ₃ <0.2%; SiO ₂ <70%.

Particle size: 0.1 to 0.5 mm.

4, fluorite

CaF ₂ >80%; Fe ₂ O ₃ <0.2%.

5, Glauber's salt

Na ₂ SO ₄ >94%; infusible residue <3%; NaCl<1.2%; CaSO ₄ <1.5%; Fe ₂ O ₃ <0.2%.

Particle size: 1.0 to 1.5 mm.

The quality of the raw materials required for the manufacture of high-grade glass is good. Not only the raw materials such as SiO ₂ , Al ₂ O ₃ , K ₂ O, Na ₂ O, CaO, MgO and the like have certain requirements, but the content does not require stability, and Fe, The harmful components such as Cd should be low. Otherwise, the glass is colored, bubbles, glassy or smeared. However, in the manufacturing of glass and certain common household utensils, when the quality of raw material can be appropriately lowered, the following types of mine tailings can consider the use of: 1, silica-rich quartz vein type gold ore, tungsten ore 2, quartzite, feldspar-rich pegmatite-type antimony ore; 3, rich in calcite , dolomite and fluorite carbonate deposits. When the content of harmful impurities is very low, it can be used to make glass separation for different purposes according to the quality of tailings.

Second, the use of tailings to melt glass

(1) Tailings dominated by feldspar as raw material for glass production

Zhuzhou Glass Factory now produces three high quality glass, the composition of which is shown in Table 2.

Table 2 Three glass product components of Zhuzhou Glass Factory

The quartz raw materials used in the plant, in addition to the sea sand in Guangdong and the quartz sandstone in Leizi, Hunan, also use the tailings of the Zhongnan 03 mine. The main minerals of the tailings are quartz and feldspar. The chemical composition is shown in Table 3.

Table 3 Chemical composition of Zhongnan 03 mine tailings

The situation in which the flat glass is produced by Zhongnan 03 Mine is as follows.

1, ingredients

The chemical composition of each raw material is shown in Table 4. The amounts of various ingredients and their calculated chemical compositions are shown in Table 5.

Table 4 Chemical composition of raw materials

Table 5 Table of chemical composition of glass ingredients

2, the production process

The various materials in Table 5 were broken (and sieved) to the desired particle size. They are respectively transported into the warehouse by air pipeline, and weighed according to the proportions in the table. After mixing, they are sent to the tank kiln and melted into a glass melt. Then they are cooled, cooled, sent to a calender for forming, and then cooled and cut. Formed into a board.

In addition, in order to save the consumption of soda ash in the glass, the Shanghai Institute of Chemical Technology recently conducted a survey on the use of granite- type tailings as a glass raw material, and conducted preliminary melting glass tests on the tailings of the two mines. From the mineral composition of the mine tailings investigated, the main minerals are feldspar, quartz, followed by mica minerals, and the chemical composition is very close. Hefei Glass Factory used porcelain stone as raw material to produce bottle and glass. Shanghai Glassware Factory and No.8 Factory of Shanghai Dailyware Company also produced brown medicinal bottles and food cans with porcelain stone and Suqian sand. Therefore, it is entirely possible to use granite type tailings as raw materials for certain glass products. The chemical composition of the ore and tailings of each type of granite is shown in Table 6.

Table 6 Chemical composition of ore and tailings of each type of granite

In the production of glass from feldspar tailings, in order to avoid staining the glass, producing bubbles, glass or stains due to excessive iron content in the tailings, it is necessary to study the iron-containing substances and symbiotic or associated minerals in the tailings. The relationship, the crystal inlay size, etc., in order to be able to separate and reduce the iron content in the tailings. For tailings with high aluminum content, it can be used to make bottle glass, alkali ball in fiber, low alkali boron-free glass, etc. From the perspective of developing new varieties of building materials, use tailings to make colored microcrystalline plate glass, color Glass-ceramic "mosaic", colored glass-ceramic facing tiles, and other glass-ceramic building materials have broad application prospects.

(2) Iron ore tailings try to make glassware

Anshan Anshan using a coke-resistant Institute beneficiation plant tailings trial glass from the vessel, a preliminary probe trial, the chemical composition shown in Table 7 tailings.

Table 7 Chemical composition of tailings in a certain plant in Anshan (%)

1. Using 84% tailings plus 16% sodium carbonate, the graphite crucible is placed in a roaster to heat it. The raw material begins to melt at 1200 ° C. When it is 1380 ° C, the crucible is taken out and the glass liquid is poured out. The glass is black in ink and has a dense structure. The glass contains unmelted small particles, and sometimes there are many bubbles in it.

2, using sodium nitrate and potassium chloride to help melt and decolorize, try the following three ingredients:

(1) Tailings: sodium carbonate: sodium chloride: sodium nitrate = 100:25:11:7, and the mixture was fired at a temperature of 1300 ° C or lower.

(2) Tailings: sodium carbonate: sodium nitrate: slaked lime = 100:25:10:15, and the mixture was fired in a crucible having a furnace temperature of 1380 °C.

(3) Tailings: sodium carbonate: sodium nitrate: slaked lime = 100:25:18:20, and the mixture was fired in a crucible having a furnace temperature of 1380 °C.

Test fruit: The glassy material produced by the (1) batching scheme is brown, opaque, and contains many fine unmelted sand grains. In the formula (2), at 1240 ° C, the sample taken out was brown, no bubbles and un-granulated particles were found; after 9 hours, the sample was dark brown at a temperature of 1270 ° C; and after 4 hours, the temperature was reached at 1320 ° C. The sample is darker and turns black. At a temperature of 1270 ° C, manual blowing and mechanical glass bottles were carried out. After cooling in air and in a cooling kiln, the results were good, but the color was black.

From this point of view, the use of tailings to melt the glass, the content of harmful components in the tailings, especially iron oxide and sulfur, etc. should not be too high, because the iron oxide in the melting process, the heat is not easy to pass to the melting In the middle of the body, the raw materials are difficult to burn through, and the color of the glass is deep. If the ore dressing method is used to remove impurities such as iron, sulfur, titanium, and chromium from the tailings, and then add other appropriate ingredients, it is entirely possible to fire the daily-use glassware.