RO116806B1 - Process for producing vitrocrystalline pyroxene materials resisting to wear and chemical agents - Google Patents

Abstract

The invention relates to a process for producing crystallized products resisting to wear and chemical agents, employed for cladding tanks in the chemical, mining and food industries, said products having an oxide composition comprising 42...55% SiO2, 9...18% Al 2 O3, 0.2...0.4% TiO2, 5.5. ...8.64% Fe2 O3; 13.4...24.10% CaO; 6.54...8.64% MgO ; 1.1...1.5% alkaline oxides. The process consists in melting a mixture comprising ash and slag resulting from steam power plants, dolomite, marble and sand at a temperature of 1450 ° C.The glass melt is pressed in adequate metal dies, the product is annealed at the temperature of 700°C then crystallized in two steps, a first step at the temperature of 750°C for an hour and the second step at the temperature of 1100°C for two hours, followed by cooling at a rate of 40°C/ for 20 hours..

Description

RO 116806 B

The invention relates to a process for obtaining pyroxenic glass-crystalline materials resistant to wear and to chemical agents that can be used for plating basins in the chemical, mining, food industry, linings for mills and grinding bodies in the ceramic industry, in the industry metallurgical, in the plating of basins and pipelines in the transport of various materials, in construction, in the plating of internal and external walls, in electrical engineering, as high voltage insulators.

Processes are known for obtaining glass-crystalline products based on mixtures of slag, molten basalt and crystallized glass.

It is known to obtain veneers by drawing from the melt into sheets with the following dimensions: 4...18 mm thick, 1800 mm wide, and with a speed of 120 ml/h, from which the necessary pieces are cut with diamond tools.

Processes are known that use natural rocks such as aplites, diabases, andesites from which, through melting and crystallization, mixtures containing dolomites, limestones, serpentinites, chromites, sands, clays are processed.

A process for obtaining some diopside-type glass-crystalline products is also known, according to which a mixture consisting of volcanic tuff, dolomite and sand is melted at a temperature of 1450°C. The glass melt is pressed into suitable molds, crystallized at 1O5O°C, and the crystallized mass is cooled at a rate of 50°C/h for 18 h.

Various glass crystalline products obtained from metallurgical slag, ash and power plant slag are known.

The chemical compositions in which they fall are the following:

SiOp ALPOPI TiOp Fe _P O _n As a MgO Na _P 0 KpO Remarks Pavluskin (1979) x 44.7- 9.3- 0.4- 7.6- 25.8- 5.9- 0.5- 1.79 Masses based on thermal power plant ash 50.1 10.3 0.6 8.5 28.6 6.5 Locsei 11970) xx 45- 12- 2,4- 1.9- 0.30- 3.44- 0.14- Masses based on furnace slag 57 20 12.9 9.20 8.29 8.80 5.30

Cr _g 0 ₃ x NMPavluskin - Osnovitehnologhii sitalov, Moskova Stvoizdat 1979, 260 p. is added as a crystallization stimulator.

xx N. Locsei - Molten Silicates and Their Properties Akadem Kiodo, Budapest 1970, 135 p.

Crystallization of the masses takes place at 9OO...95O°C [Pavlus Kin] and the compositions synthesized by Loczei at 1OOO°C.

as mineralogical compositions, diopside-albite, melilite-akermanite, wollastonite, hedenbergite associated with diopside, angite with a monoclinic pyroxene are most commonly encountered.

The process according to the invention achieves obtaining pyroxenic glass-crystalline materials of the diopside-hedenbergite type that belong to the CaO-MgC-SiO ₂ + [AI ₂ 0 ₃ , Fe ₂ 0 ₃ ] system whose composition varies between 42...55% Si0 ₂ , 9 ...18% AI ₂ 0 ₃ , 0.2...0.4% TiO ₂ , 5.5...8.64% Fe ₂ 0 ₃ , 13.14...24.10% CaO, 6.54...8.64% MgO and 1.1...1.5% alkali oxides, and widens the range of known products in that, for the preparation of crystallized glass, a mixture consisting of 35...60% is melted power plant ash or slag, 20...30% dolomite, 0...21% marble waste, 10...20% sand, 1...2.5% Cr ₂ 0 ₃ , at a temperature of 142O. ..145O°C while maintaining a level of

Claims (5)

RO 116806 Β 2 h, the crystallization being carried out in two stages, at 750°0 with a step every 1 h and at 11OO°C with a step every 2 h, the speed of raising the temperature being 5°C/min, and the cooling, with 40°C/h for 20 h. The advantages of the process according to the invention consist in the fact that the veneers in the bunkers and ditches made from materials thus obtained last 5...6 years, while the metal linings last 5...6 months. in addition, in this way the ash and slag are incorporated into a product with a special use value, being superiorly utilised. An embodiment of the invention is given below. For the preparation of pyroxenic glass, resistant to wear and chemical agents, a mixture consisting of 35...60% power plant ash or slag, 20...30% dolomite, 0...21% marble waste, is melted. 10...20% sand, 1...2.5% Cr ₂ O ₃ , at a temperature of 142O...145O°C with a 2 h buffer. The glass thus obtained by melting the mixture is cooled to 700° 0 for 1 h and then crystallized in two steps; stage I at a temperature of 750°C with a step every 1 h and stage II at a temperature of 1100°C with a step every 2 h. The speed of raising the temperature is 5°C/min and cooling by 40°C/ h for 20 h. The definitive microstructure consists of 90% crystalline phase consisting of diopside having hedenbergite in solid solution, the crystals reaching a maximum of 2.5... 3 p.m. The remaining 10% of the sample volume is the vitreous phase. Power plant ash and 65 slag-based masses have the same microstructure, mineralogical composition and physico-chemical properties. Among the properties that condition the possibilities of use, the following are mentioned: - resistance to wear by abrasion...................0.019 g/cm ² 70 - hardness on the Mohs scale 7...8 - coefficient of linear thermal expansion ................ 6.42.10^0 ¹ - heat resistance 360°0 - weight loss after boiling for one hour in:75 - HCI (conc. 20.24%) ..........................0.145% - H ₂ S0 ₄ (conc. 50%)............................0.06% - NaOH (conc. 35%) .......................... 0.225%. As a result of the presented properties, the produced material can be used for linings for ore and coke bunkers, drains, veneers for basins with 8o hot aggressive substances, substitute for agate in fine mechanics, linings for mills and grinding bodies in ceramics. Claim Process for obtaining pyroxenic glass materials resistant to wear and chemical agents, having an oxide composition that varies between 42...55% Si0 ₂ , 9...18% AI ₂ 0 ₃ , 0.2...0, 4% Ti0 ₂ , 5.5...8.64% Fe ₂ 0 ₃ , 13.14...24.10% CaO, 6.54...8.64% MgO and 1.1... 1.5% alkaline oxides, made by crystallizing a glass, characterized by the fact that, for the preparation of crystallized glass, a 90% mixture consisting of 35...60% power plant ash or slag, 20...30% dolomite is melted, RO 116806 B □...21% marble waste, 10...20% sand, 1...2.5% CrgOg, at a temperature of 1420...1450°0 with a 2-hour standstill, crystallization taking place in two stages, stage I, at a temperature of 750°C, with a step every 1 h, and stage II, at a temperature of 1100°C, with a step every 2 h, the speed of raising the temperature being 5°C/min, and cooling, with 40°C/h for 20 h, after which the processing of the products is carried out in a known way, by casting and pressing in metal molds, or the glass powder is synthesized. The president of the examination committee: Eng. Georgescu Mirela Examiner: chem. Stefan Rodica Editing and computerized techno-editing - OSIM Printed at: State Office for Inventions and Trademarks