Pyrohydrolysis of Metal

Chlorides Feasibility

StudyOliver Gnotke, Kronos International, Inc. & Jim

Berthold, OLI (speaker)

OLI Simulation Conference October 25, 2016

• Production titanium dioxide creates significant amounts of an aqueous metal chloride solution as a by-product. – Land filling of the solid residue is the normal waste removal process

– pyrohydrolysis is a viable way to convert metal chlorides from TiO2 production into the valuable products hydrochloric acid and metal oxides with iron oxide as main component.

• The metal chloride solutions are complex highly concentrated aqueous solutions of di- and trivalent iron chlorides, other metal chlorides and hydrochloric acid.

• Kronos followed a theoretical approach for a feasibility study to assess the pyrohydrolysis process. – As a first step it was essential to evaluate the applicability of OLI Stream Analyzer for

metal chloride solutions.

– For the simulation of a pyrohydrolysis process especially the prediction of solubility limits of salts and vapor pressures of HCl are important .

– Available literature data was taken for the system FeCl2-HCl-Water and compared with OLI results. The deviation of OLI results and literature data were quite small. This qualified OLI as a valuable tool for the feasibility study.

Abstract

• Pyrohydrolysis: Convert metal chloride solution

into metal oxide and HCl

• Reaction is carried out in fluidized bed or spray

tower at temperature of 600-800°C

• HCl is recovered from gas stream by absorption

columns

Pyrohydrolysis Reaction

4 FeCl2 + 4 H2O + O2 2 Fe2O3 +8 HCl

2 FeCl3 + 3 H2O Fe2O3 +6 HCl

Manufacturing of Titanium Dioxide & potential benefit of

Pyrohydrolysis

Chloride

Process

Rutile

HCl

Leaching

Ilmenite

(High Iron

content)

Neutralisation

& Landfill

Metal

Chloride Pyrohydrolysis

Metal

Chloride Pyrohydrolysis

HCl

Chlorine

TiO2

Metal Oxide

HCl for sale

HCl

Metal chloride solution

Metal chloride solution

PROCESS

Zr, Nb) Steelworks Nickel Production

Metal Separation

Ore Processing Scrap

Pickling Line

Dissolving Station

Extraction Liquid

Extraction Liquid

Dissolving Station

Reactor

Fuel

Air

Cyclone

Venturi

Separator

Absorber Scrubber

Fan

Stack

Off-Gas

Regenerated Acid Treated Oxide Oxide

• Reactor, Cyclone,

Oxide Station

• Preconcentration

• HCl-Absorption

• Gas Cleaning

System

Process Stages:

KRONOS project

• Feasibility Study for Pyrohydrolysis using

OLI

• No pilot unit available

• Economic assessment

• First step: Check OLI Stream Analyzer

results against available literature data

• 0,16 kg/kg HCl und 0,16 kg/kg FeCl2

Vapour Pressure as a function of temperature

0

0,1

0,2

0,3

0,4

0,5

0,6

40 50 60 70 80 90 100

Pre

ssu

re [

ba

r]

Temperature [°C]

Literature

OLI

• Comparison OLI with literature data [Che70 ] @70°C, FeCl2-conc. 0,78

mol/l

• OLI Bubble point calculation, variable pressure

Gas phase composition in the system FeCl2-Water-HCl

0,0001

0,001

0,01

0,1

1

0,00 0,10 0,20 0,30

Mo

l% H

Cl

in g

as p

ha

se

HCl liq. conc. [kg/kg]

Literature OLI

• Comparison OLI with literature data [Che70 ] @70°C, FeCl2-conc.

0,78 mol/l

• Good prediction of azeotrope

System pressure

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,00 0,05 0,10 0,15 0,20 0,25 0,30

To

tal

pre

ssu

re [

ba

r]

HCl-conc. liq.[kg/kg]

Literature

OLI

• HCl concentration in gas phase higher with addition of FeCl2

• Azeotrope shifted by FeCl2 addition

• Solutions with high salt concentrations could deliver over azeotropic hydrochloric acid

(i.e. > 20% HCl)

OLI prediction on influence of FeCl2

1,00E-04

1,00E-03

1,00E-02

1,00E-01

1,00E+00

0 0,1 0,2 0,3

Mo

l% H

Cl

in g

as p

ha

se

HCl liq. conc. [kg/kg]

OLI with FeCl2

OLI without FeCl2

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0 0,1 0,2 0,3

Pre

ssu

re [

ba

r]

HCl-conc. liq [kg/kg]

OLI with FeCl2

OLI without FeCl2

FeCl2 /FeCl3 in HCl solubility data from OLI database

0

10

20

30

40

50

60

0 10 20 30 40

wt%

-FeC

l2

wt%-HCl

0C

20C

40C

60C

100C

FeCl2.2H2O

FeCl2.4H2O

FeCl2.6H2O

FeCl2.4H2O

FeCl2.2H2O

0

5

10

15

20

25

30

0 5 10 15 20 25 30m

-FeC

l3

m-HCl

t=25C

FeCl3.6H2O

FeCl3.3.5H2O

FeCl3.2.5H2O

FeCl3.2H2O

FeCl3.HCl

OLI comparison MgCl2 solubility in HCl

0

5

10

15

20

25

30

35

40

0 5 10 15 20 25 30 35 40 45 50

Mg

Cl2

, w

eig

ht

%

HCl, weight %

Magnesium Chloride Solubility in Hydrochloric Acid

-20C

-8C

0C

25C

38C

48C

60C

70C

• Good prediction of OLI both in

– VLE

– Solubility

• Valuable tool for the chloride system

• Next possible step

– Coupling of OLI with ASPEN for full flowsheet

simulation of Pyrohydrolysis

– Aspen needed for high temperature

equipment

Conclusions

• [Che70] Chen, McGuire, Lee: Vapor-Liquid Equilibria of the Hydrochloric Acid-Ferrous

Chloride-Water System. Journal of Chemical and Engineering Data, Vol. 15, No.2, 1970

• [Sch52] Schimmel, F.A.: The Ternary System Ferrous Chloride-Hydrogen Chloride-

Water, Ferric Chloride-Ferrous Chloride-Water, 1952

• Pyrohydrolysis: Fundamentals and Applications for the Ferrous and Non-Ferrous Metallurgy,Dr.

Frank H. Baerhold, Dr. Albert Lebl, Rewas '99: Global Symposium on Recycling, Waste Treatment

and Clean Technology by I. Gaballah (Editor), J. Hager (Editor), R. Solozabal (Editor)

Literature

• Dr.-Ing. Oliver Gnotke, born 1971 in Düsseldorf /Germany is the team leader Chloride Process development for Kronos International, Inc., Leverkusen/Germany a leading producer of titanium dioxide with 6 production locations worldwide. He works for Kronos since 12 years having positions in different technical departments. His main responsibility is the optimization of the production sites with respect to cost, quality and throughput. He has wide experience with CAE tools as for example flowsheet simulation, CFD and thermodynamic properties estimation.

• Prior to his work for Kronos he worked from 1999-2004 as research assistant at the Chair of Energy Technology, University of Darmstadt/Germany. His main research topics were experimental studies and simulation of multiphase flow in chemical and power plants. Graduated 2004 to PhD (Dr.-Ing.).

• He started his studies as Chemical Engineer at the University of Dortmund, Germany. During university studies he made several internships in the chemical industry as Bayer, Henkel, CFPI (France) and Lurgi Engineering where he optimized polymerization reaction using numerical simulations.

Biography