Fluid-Solid Reactions

H. Y. Sohn

• Publisher: Elsevier
• Year: 2020
• Print ISBN: 9780128164655
• eBook ISBN: 9780128164662
• Edition: 2
• Topic: Physical Sciences
• Subtopic: Organic Chemistry

Fluid-Solid Reactions, Second Edition takes a detailed and thorough look at the scope of fluid-solid reaction systems, focusing on the four phenomena: external mass transfer, pore diffusion, chemical reaction, and adsorption/desorption. This completely revised new edition builds on the classic original edition through the introduction of cutting-edge new theories and applications, including the formulation and application of a new and convenient law that governs fluid-solid reaction kinetics. This book will be of primary interest to practicing engineers engaged in process research, development, and design in the many fields where fluid-solid reactions are critical to workflow and research.

Fluid-solid reactions play a major role in the technology of most industrialized nations. These reactions encompass a very broad field, including the extraction of metals from their ores, the combustion of solid fuels, coal gasification, and the incineration of solid refuse.

• Features 50% new and revised content, arming researchers with the latest developments in the field
• Details a new unified approach to modeling the rates of fluid-solid reaction systems
• Authored by one of the world's foremost experts on fluid-solid reactions and their applications in the field

Chapter 1

Introduction

Abstract

This chapter introduces the subject matters, their importance in research and industrial applications, major components in the theoretical analysis of fluid-solid reactions, and how the book is organized with a brief summary of each chapter.

Keywords

fluid–solid reactions; blast furnace; fluidized bed roaster; flash smelting furnace; classification; theoretical development; intermediate steps; chapter organization

Fluid-solid reactions, both gas-solid and liquid-solid types, play a major role in most industrial technologies. They encompass a very broad field, including the extraction of metals from their ores (ironmaking in blast furnaces, the roasting of sulfide ores, flash smelting, leaching of minerals from ores, etc.), the combustion of solid fuels, coal gasification, cement manufacture, dissolution of solids in liquids, and crystallization to name a few examples (Sohn and Wadsworth, 1979; Szekely et al., 1976). They are also critical in a wide range of other fields from environment-related systems such as carbon dioxide sequestration (Liu and Mostaghimi, 2017; Menke et al., 2015; Chen et al., 2014) to several aspects of semiconductor processing (Chiang et al., 2017; Dodge and Shadman, 2014). Equipment used for effecting fluid-solid reactions is also diverse, as seen from Figs. 1.1 to 1.3.

Figure 1.1 Schematic diagram of an iron blast furnace. With permission from JFE21st Century Foundation. Adapted from: <https://www.google.com/search?biw=1282&bih=609&tbm=isch&sa=1&ei=tAUeXp-LGbrL0PEPjseaqAg&q=JFE+steel+blast+furnace&oq=JFE+steel+blast+furnace&gs_l=img.12…65027.66330…69331 …0.0…0.111.325.3j1……0…1…gws-wiz-img……0i8i7i30.Dz46jibTUSg&ved=0ahUKEwiftbDU2YPnAhW6JTQIHY6jBoUQ4dUDCAc#imgrc=_> (accessed 14.01.20.).

Figure 1.2 A schematic of a bubbling fluidized bed gasifier for biomass. With permission from ANDRITZ. Adapted from: <https://www.ieabioenergy.com/publications/liquid-transportation-fuels-via-large-scale-fluidisedbed-gasification-of-lignocellulosic-biomass/> (accessed 15.01.20.).

Figure 1.3 Schematic diagram of a copper smelting flash furnace. With permission from Total Materia. Adapted from: <https://docplayer.net/15217624-Eco-efficient-solutions-in-the-finnish-metallurgical-industry.html> (accessed 05.09.17.).

Fig. 1.1 is a schematic line diagram of a typical iron blast furnace in which iron ore is reduced and molten hot metal is the product. A large iron blast furnace may have an internal volume of 6000 m³ and produce almost 6 million tonnes of iron per year, enough to produce 6 million passenger cars yearly (e-metallicus, 2017). The blast furnace is fed with ore, pellets, or sinter, which may range in size from 1 to 10 cm.

Fig. 1.2 is a schematic diagram of a fluidized bed roaster for sulfide ores. The solid reactant supplied to such a system is carefully sized and may be of the order of 0.01–0.2 cm.

Fig. 1.3 is a schematic diagram of a copper flash smelting furnace, in which a copper concentrate of particle size <100 µm is reacted with an oxygen-containing process gas to produce a copper matte in the typical first step of coppermaking.

Fluid-solid reactions may be grouped into the following general types:

1. A. Solid→Fluid
2. B. Solid 1→Fluid+Solid 2
3. C. Fluid+Solid→Fluid
4. D. Fluid+Solid 1→Fluid+Solid 2
5. E. Fluid+Solid 1→Solid 2
6. F. Solid 1+Solid 2→Fluid+Solid 3
7. G. Solid 1+Solid 2→Solid 3+Solid 4 (if proceeding through fluid intermediates)
8. H. Fluid→Fluid+Solid
9. I. Fluid→Solid

Each aforementioned phase may consist of more than one compound. A fluid phase may contain an inert fluid component, the presence of which may significantly affect mass transfer.

Although some of the aforementioned reactions are the reverses of others, for example, Types A and I, their mechanisms and rate expressions are usually very different, that is, those for one cannot be applied to the other. This is because the mechanisms and kinetics of fluid-solid reactions depend critically on the structure of the solid. Thus fluid-solid reactions cannot in general be termed “reversible” in the sense of reversible homogeneous reactions. Fluid-solid reactions with finite equilibrium constants should be termed “equilibrium-limited” reactions, because the same rate equation does not apply to the reverse reaction simply with a change of the sign on the concentration driving force. The fluid product concentration in this case just reduces the concentration driving force for the forward reaction, and a different rate expression must be applied when the product concentration exceeds the equilibrium value, that is, the reverse reaction must be considered as a different type of fluid-solid reaction.

Of the aforementioned groups, Type D is arguably most widely encountered in chemical and metallurgical processes, and thus will receive the greatest attention in this book, followed by Types C and F.

Some real examples of fluid-solid reactions are (ΔH° values at 25°C)

1. 1. $\mathrm{C}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)={\mathrm{CO}}_2\left(\mathrm{g}\right);\mathrm{\Delta }H°=-94.1\mathrm{kcal}/\mathrm{mol}$
   
2. 2. $\mathrm{FeO}\left(\mathrm{s}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)=\mathrm{Fe}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right);\mathrm{\Delta }H°=+6.5\mathrm{kcal}/\mathrm{mol}$
   
3. 3. $\mathrm{FeO}\left(\mathrm{s}\right)+\mathrm{CO}\left(\mathrm{g}\right)=\mathrm{Fe}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right);\mathrm{\Delta }H°=-3.3\mathrm{kcal}/\mathrm{mol}$
   
4. 4. ${\mathrm{FeS}}_2\left(\mathrm{s}\right)+11/4{\mathrm{O}}_2\left(\mathrm{g}\right)=½{\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)+2{\mathrm{SO}}_2\left(\mathrm{g}\right);\mathrm{\Delta }H°=-199\mathrm{kcal}/\mathrm{mol}{\mathrm{FeS}}_2$
   
5. 5. $\mathrm{C}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)=2\mathrm{CO}\left(\mathrm{g}\right);\mathrm{\Delta }H°=+41.2\mathrm{kcal}/\mathrm{mol}\mathrm{C}$
   
6. 6. $\mathrm{FeO}\left(\mathrm{s}\right)+\mathrm{C}\left(\mathrm{s}\right)=\mathrm{Fe}\left(\mathrm{s}\right)+\mathrm{CO}\left(\mathrm{g}\right);\mathrm{\Delta }H°=+37.9\mathrm{kcal}/\mathrm{mol}$
   
7. 7. 4CuFeS₂ (s)+17O₂ (dissolved in liq.)+4H⁺ (in liq.)=4Cu²⁺ (
   
   )+4Fe³⁺ (
   
   )+$8\mathrm{S}{\mathrm{O}}_4^{2-}$
   
   (
   
   )+2H₂O (
   
   )

Of these reactions, the oxidation (combustion) of carbon and the oxidation (roasting) of pyrite are both highly exothermic, while the reduction of iron oxide with hydrogen is slightly endothermic. Both the reaction of carbon dioxide with carbon and the reaction of ferrous oxide with carbon are strongly endothermic. It is perhaps of interest to make some comments on the characteristics of the reactions listed.

Systems 1 and 5 involve reaction between a fluid and a solid wher...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Preface
• Acknowledgments
• Chapter 1. Introduction
• Chapter 2. Constitutive elements of fluid-solid reactions
• Chapter 3. Reaction kinetics of fine particles
• Chapter 4. General approach to fluid-solid reaction analysis and modeling
• Chapter 5. Reactions of single nonporous solids
• Chapter 6. Reactions of single porous solids
• Chapter 7. Sohn’s law of fluid-solid reaction rates
• Chapter 8. Extension of basic analysis to complex systems
• Chapter 9. Reactions between solids proceeding through gaseous intermediates
• Chapter 10. Design of multiparticle fluid-solid reactors
• Chapter 11. Experimental techniques in fluid-solid reactions
• Index