Cement Free Magnesia Based Castables Versus Magnesia-Spinel Bricks in Cement Rotary Kilns

It is well known that doloma bricks present better coating adherence than magnesia–spinel bricks when applied in cement rotary kilns, which is related to the different coating formation mechanism. The coating has an essential role in prolonged operation by protecting the refractory lining; thus, it is important to improve its adherence on magnesia–spinel refractories. The objective of this investigation is to study different compositions of magnesia–spinel bricks, achieved by varying additives used (calcined alumina, limestone, hematite and zirconia) and firing temperature (1500 °C and 1700 °C), to enhance the coating adherence measured by the sandwich test. The results have pointed out that the use of higher firing temperature contributes positively to physical adherence due to well-sintered refractory structure and elevated permeability, attaining coating strength superior to 2 MPa. For the chemical adherence, the addition of 2 wt.% of limestone increased the coating strength to 3 MPa, but resulted in a drop in hot properties. In this context, the most suitable approach to improve adherence of clinker coating and maintain hot properties in suitable levels is to increase the firing temperature.

Download Full-text

Qualitative and Quantitative Coating Tests: A Comparison in Magnesia–Spinel Refractory Bricks

Ceramics ◽

10.3390/ceramics3010014 ◽

2020 ◽

Vol 3 (1) ◽

pp. 144-154 ◽

Cited By ~ 1

Author(s):

Graziella Pacheco ◽

Geraldo Eduardo Gonçalves ◽

Vanessa Lins

Keyword(s):

Thermomechanical Properties ◽

Contact Method ◽

Test Results ◽

Protection Mechanism ◽

Subjective Analysis ◽

Qualitative And Quantitative ◽

Magnesia Spinel ◽

Rotary Kilns ◽

Refractory Bricks ◽

Adherence Ability

In cement processing, which involves the production of clinker in rotary kilns, the main refractories used in the transition and burning zones are magnesia–spinel bricks. These bricks present suitable chemical and thermomechanical properties, not to mention that they can be easily landfilled. Among the main wear mechanisms of these bricks in the kiln, the infiltration of alkaline salts is noteworthy and occurs through the open pores of the refractory. In this way, the coating—a clinker layer adhered to the brick surface—appears as a protection mechanism of the lining against infiltration. Thus, the objective of this investigation is to run a qualitative coating test based on the contact method, and quantitative coating test based on the sandwich method to check the suitability of the methodologies and to evaluate the coating adherence on two different magnesia–spinel bricks. It was possible to distinguish the superior adherence ability of brick B in both coatings due to the higher porosity and the presence of nonreacted ZrO2. Despite the similarity between the test results, the quantitative sandwich-coating test is preferable because it does not depend on subjective analysis.

Download Full-text

Development of Magnesia-Spinel Brick for Transition Zone in Cement Rotary Kilns under the Vastly Increasing use of Waste

Proceedings of the Unified International Technical Conference on Refractories (UNITECR 2013) ◽

10.1002/9781118837009.ch36 ◽

2014 ◽

pp. 205-209

Author(s):

Makoto Ohno ◽

Hitoshi Toda ◽

Kozo Tokunaga ◽

Yoshiki Tsuchiya ◽

Yoshio Mizuno

Keyword(s):

Transition Zone ◽

Magnesia Spinel ◽

Rotary Kilns

Download Full-text

A New Design for Energy Saving in the Rotary Kilns of Cements Plants

International Review of Mechanical Engineering (IREME) ◽

10.15866/ireme.v13i10.17147 ◽

2019 ◽

Vol 13 (10) ◽

pp. 587

Author(s):

Soukaina Mounkid ◽

Abdellatif Loukili

Keyword(s):

Energy Saving ◽

Rotary Kilns

Download Full-text

Problems with Refractories for Rotary Kilns and Their Factors

JAPAN TAPPI JOURNAL ◽

10.2524/jtappij.73.770 ◽

2019 ◽

Vol 73 (8) ◽

pp. 770-773

Author(s):

Hitoshi Toda

Keyword(s):

Rotary Kilns

Download Full-text

Simulation of the Control System of the Coke Calcination in Tubular Rotary Kilns

Russian Metallurgy (Metally) ◽

10.1134/s0036029520130091 ◽

2020 ◽

Vol 2020 (13) ◽

pp. 1600-1606

Author(s):

T. V. Dontsova ◽

K. G. Kozulin ◽

T. V. Piskazhova ◽

G. B. Danykina

Keyword(s):

Control System ◽

Rotary Kilns

Download Full-text

Modeling of lime production process using artificial neural network

Chemical Product and Process Modeling ◽

10.1515/cppm-2021-0032 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Abolghasem Daeichian ◽

Rana Shahramfar ◽

Elham Heidari

Keyword(s):

Neural Network ◽

Artificial Neural Network ◽

Production Process ◽

High Energy ◽

Ann Model ◽

Artificial Neural ◽

Rotary Kilns ◽

Input Variables ◽

Artificial Neural Network Ann ◽

Lime Production

Abstract Lime is a significant material in many industrial processes, including steelmaking by blast furnace. Lime production through rotary kilns is a standard method in industries, yet it has depreciation, high energy consumption, and environmental pollution. A model of the lime production process can help to not only increase our knowledge and awareness but also can help reduce its disadvantages. This paper presents a black-box model by Artificial Neural Network (ANN) for the lime production process considering pre-heater, rotary kiln, and cooler parameters. To this end, actual data are collected from Zobahan Isfahan Steel Company, Iran, which consists of 746 data obtained in a duration of one year. The proposed model considers 23 input variables, predicting the amount of produced lime as an output variable. The ANN parameters such as number of hidden layers, number of neurons in each layer, activation functions, and training algorithm are optimized. Then, the sensitivity of the optimum model to the input variables is investigated. Top-three input variables are selected on the basis of one-group sensitivity analysis and their interactions are studied. Finally, an ANN model is developed considering the top-three most effective input variables. The mean square error of the proposed models with 23 and 3 inputs are equal to 0.000693 and 0.004061, respectively, which shows a high prediction capability of the two proposed models.

Download Full-text