PL201196B1 - Method for the manufacture of the refractory cement - Google Patents

Abstract

A method for producing a refractory alumina cement, characterized in that a raw material mixture containing alumina, limestone and dolomite is fired at a temperature of 1150-1520°C while maintaining a heating rate of at least 150°C/hour.

Description

(12) PATENT DESCRIPTION (19) PL (11) 201196 (13) B1 ( ²¹ ) Application number: ³⁷⁴¹³⁴ ) HtCI.

C04B 7/32 (2006.01) (22) Date of filing: 04/04/2005 (54)

Method for producing refractory cement

(73) Patent holder: Institute of Glass, Ceramics, Refractory and Construction Materials, Warsaw, Poland (43) The application was announced: (72) Inventor(s): 16/10/2006 BUP 21/06 Józef Sawków, Gliwice, PL (45) The patent was granted on: Józef Wojsa, Gliwice, PL Jerzy Czechowski, Gliwice, PL Jacek Podwórny, Gliwice, PL Józef Barański, Gliwice, PL 31/03/2009 WUP 03/09 (74) Representative: Marshal Jeremi, Refractory Materials Department of ISCMOiB

(57) 1. A method for producing a fire-resistant alumina cement, characterized in that a raw material mixture containing alumina, limestone and dolomite is fired at a temperature of 1150-1520°C while maintaining a heating rate of at least 150°C/hour.

PL 201 196 B1

Description of the invention

The subject of the invention is a method for producing refractory alumina cement.

Cements containing 40 to 70% by weight of Ά^Θβ are known, with high hydraulic activity after 24 hours of hardening and a typical refractoriness of approximately 1650°C. Such cements are used in monolithic materials operating at temperatures up to 1600°C. Aluminous cements consisting of calcium aluminates and possibly corundum additives are not resistant to the action of strongly alkaline metallurgical slags, which seriously limits their use in concretes used in metallurgy and industrial thermal equipment.

The aim of the invention is to obtain an alumina cement that will provide concrete with good hydraulic, fire and resistance properties, especially in terms of their corrosion resistance to metallurgical slags of high alkalinity.

This objective was achieved by producing and grinding clinker consisting mainly of CA and Mg, where CA is CaO Al ₂ C>3 and Mg is MgO Al ₂ O3, this is achieved by subjecting a raw material mixture containing alumina, limestone and dolomite to firing at a temperature of 1150 to 1520°C using a heating rate of at least 150°C/hour, wherein the raw material mixture subjected to firing contains:

52-60% by weight of alumina

40-49% dolomite by weight

0-24% by weight of limestone, and the produced clinker is ground into cement with a grain size corresponding to a specific surface area of at least 3200 cm ² /g.

The resulting aluminate-spinel cement, despite having a lower calcium aluminate content than aluminate cements, exhibits high hydraulic activity due to the small size of calcium aluminate crystals, which range from 0.3 to 10 µm and usually do not exceed 3 µm. This size of calcium aluminate crystals is caused by the fact that during firing, the MA spinel crystals that form inhibit the growth of CA aluminate crystals due to the expansion accompanying the formation of spinel in the aluminate-spinel clinker.

Despite its low calcium aluminate content, the cement according to the invention exhibits favorable hydraulic properties and a typical refractoriness of approximately 1630°C. Furthermore, it provides refractory concretes with high resistance to highly alkaline metallurgical slags. Corundum, spinel-corundum (MA-alphaA), and spinel (MA) aggregates should be used to prepare refractory concretes from aluminate-spinel cement.

The method of producing refractory cement according to the invention is presented in the examples:

Example 1:

Alumina-spinel clinker is produced by firing a homogenized raw material at 1500°C, consisting of 55% alumina dust with a minimum content of 99% _Al2O3 and 45% pure dolomite with an admixture level of up to 0.8%. The raw material is sintered into clinker at a kiln heating rate of ~300°C/hour. The produced clinker is ground without additives into cement with a grain size corresponding to a specific surface area according to Blaine of at least 3200 ^cm2 /g.

Example 2:

The raw material composition for the production of aluminate-spinel clinker consists of 5.2% alumina with an _Al2O3 content of at least 99%, 24% limestone with an admixture level of up to 0.5%, and 24% pure dolomite with an admixture content not exceeding 0.8%. The homogenized raw material composition is sintered into clinker in a kiln heated at a temperature of approximately 300°C/hour. The produced clinker is ground without additives into cement with a specific surface area according to Blaine of at least 3200 ^cm2 /g.

Properties of the obtained cements:

Main phases: calcium monoaluminate-CA, Spinel MA in the presence of an admixture of calcium dialuminate and corundum.

Setting time according to Vicat: start 2 hours 55 minutes, end 6 hours 50 minutes.

Normal refractoriness at oxidizing temperature - 1627°C

One-day compressive strength of concrete according to BN-82/6761-15, bound with aluminate-spinel cement - 82.5 MPa.

One-day flexural strength of concrete as above: 9.8 MPa.

Bending strength of concrete as above after firing at 1500°C/2h - 10.8 MPa

Compressive strength of concrete as above after firing at 1500°C/2h - 26.3 MPa

Linear changes of concrete as above after firing at 1500°C/2h: +2.18%.

PL 201 196 B1

Claims (2)

Patent claims A method for producing refractory alumina cement, characterized by firing a raw material mixture containing alumina, limestone and dolomite at a temperature of 1150-1520 ° C while maintaining a heating rate of at least 150 ° C / hr. 2. The method according to p. A method as claimed in claim 1, characterized in that the raw material mixture subjected to firing comprises: 52-60 wt.% alumina 40-48 wt.% dolomite 0-24 wt.% limestone, and the clinker produced is ground into cement with a grain size corresponding to a specific surface area of at least 3200 cm ² / g.