Titanium. There isn’t another metal with the exceptional overall properties of titanium: tough, strong, light weight, exceptional corrosion resistance, and performance even at extreme temperatures.
TITANIUM ADVANCED METALLURGY
Consider titanium
Ti
Titanium 22
THE KROLL PROCESS
Metals are found in nature as minerals, i.e., metal compounds. Titanium, for example, occurs as rutile, which is titanium dioxide and as ilmenite, which is iron titanate. Titanium metal is traditionally produced by the Kroll Process, a chemical reaction of titanium tetrachloride with magnesium. The titanium product is termed metal sponge which must be melted to remove entrained salt. Titanium tetrachloride is prepared by carbochlorination of rutile, a process that produces toxic dioxin as a byproduct. The tetrachloride is subjected to multiple distillation steps to rid the feedstock of impurities. Such a facility comes with high CapEx, runs with high OpEx and generates high levels of pollutants.
The process of turning rutile or ilmenite into titanium is fundamentally difficult and the many steps involved in the Kroll process adds to the cost. The Kroll process for titanium has changed little since the 1950s. There is a better way.
The Kroll faces these challenges:
Huge facility spanning large area
Long permitting time
High labor intensity
Batch process with long cycle time (~12 hours)
Yield discrete batches-not continuous flow
High level of impurities
Tremendous energy cost
High carbon intensity
Huge waste
THE SADOWAY PROCESS
Consider a process in which titanium dioxide is dissolved in a solvent composed of a solution of other metal oxides into which are immersed two electrodes. By the action of electric current the titanium dioxide is decomposed into liquid titanium which pools on the bottom of the cell and into oxygen which vents through the top of the cell. No Kroll reactor, no carbochlorinator, no vacuum arc remelting furnace.
In one step we move from dirt to liquid metal of requisite purity, and at or below the market price point. One-pot smelting. Processing compression.
High-temperature electrochemistry is a platform technology that can be adapted for processing other ores and converting them into their respective metals, e.g., titanium, antimony, scandium, beryllium, vanadium, and rare earths (neodymium and samarium).
The processing compression in Sadoway High-Temperature Electrolysis significantly reduces the number of steps with attendant savings in CapEx and OpEx—power, CO2 emissions, footprint-- as well as labor, equipment, transportation, permitting time, and related expenses.
The Sadoway system:
Two buildings: extractory and refinery.
Each building holds 10x10x10’ cells in 2x2 rows.
Yield continuous flow which translated into exceptionally high space-time yield
Zero to no waste or emissions
ELEMENTAL TARGET METAL
Comparison of titanium processes
Producing titanium with the Sadoway process saves cost of power, smelter, labor, and time, as compared to the legacy Kroll process. In one step, we move from dirt to liquid metal of requisite purity, well below below the market price point. One-pot smelting without CO2 emissions and the by-product dioxins.
1 - PURIFY TIO
Roast, HC leach, calcine1-DISSOLVE
TiO, into a molten oxide bathelectricity in
FLOW CHART COMPARISON
Compare the Kroll, and the HAMR process with the Sadoway process
KROLL PROCESS
CHLORINE, MAGNESIUM, A SOLID SPONGE AND A REMELT • MOE REPLACES ALL FIVE STEPS WITH ONE CELL
CHLORIDE ROUTE - 5 STEPS
CO2 out
chloride + coke in
1-CHLORINATE
TiOz + coke + Clz→ TiCL42 • PURIFY TICI4
Distil out V, Si, Fe chloridesmagnesium in
2-HAMR REDUCE
TiO, + 2Mg + H2 → TiH≥ + 2Mgo2-ELECTROLYSIS
Liquid Ti at cathode, O, at anode3-TAP + CAST
Liquid titanium → ingot3-KROLL REDUCE
TiCl4 + Mg → Ti sponge, batch4-SPONGE
Crush, leach, press electrodes5-VACUUM REMELT
Melt 2-3 times → ingotHAMR PROCESS
NO CHLORINE • STILL MAGNESIUM • ADDS HYDROGEN • MgO LEFT BEHIND • POWDER, NOT INGOT
TiO, FEEDSTOCK
rutile, slag or synthetic any Ti0z-rich oxideHYDROGEN-ASSISTED MAGNESIOTHERMIC REDUCTION • 5 STEPS
3-LEACH + DEOX
HCl leach; Mg + H, to <0.2% 04-DE-HYDROGENATE
TiH, → Ti powder, vacuumSADOWAY PROCESS
NO CHLORINE • NO MAGNESIUM - NO HYDROGEN - NO SPONGE • NO REMELT-electrons are the reductant; oxygen the only by-product
HIGH-TEMPERATURE ELECTROLYSIS • 3 STEPS
MgClz out (recycled to Mg)
5-CONSOLIDATE
Sinter parts, or melt to ingotTITANIUM METAL
Ingot, billet or powder three reductantsoxygen out
One metric tonne output of titanium
Comparison:
Kroll process v. Sadoway process
Power cost
$3,585
Kroll process
$40
Sadoway process
Cost for power--assumes .05¢ KWh or $50 MWh.
Smelter land requirement
75 acres
Kroll process
1 acre
Sadoway process
Kroll process requires over 75 acres per one tonne annual output. Sadoway process requires ~1 acre per one tonne annual output.
CO2 emissions
28 tonnes
Kroll process
.919 tonnes
Sadoway process
C02 emissions per one metric tonne output of titanium.
Kroll process produces 28 tonnes or 28,000 Kg. Sadoway process produces 0.919 tonnes or 919 Kg.
Titanium experiments carried out at MIT and 22Ti
Titanium pooled at the bottom of crucible
PROOF OF CONCEPT
Work performed in 1999 by Prof. Sadoway at MIT, and at the Sadoway/Yurko start up 22Ti, is evidence of conversion of rutile into liquid titanium by molten beryllate electrolysis.
Experimental conditions
Melt- BeO 42%(mol), CaO 28%(mol), TiO2 30%(mol)
Cathode – Mo rod
Anode- Carbon rod
Electrolysis carried out at 1700℃ in a Mo crucible. A constant current of 10A was passed through the cell over 4-hr period. Cell voltage remained between ~0.9-1.1V throughout the run.
Observations
Silver colored deposit was observed in the bottom of crucible.
Analysis
Crucible surface and the melt were analyzed by EDX and XRD. Both methods indicated the presence of liquid Titanium.
SEM-EDX analysis of the bottom
WHY IS THIS IMPORTANT?
In the lab, Sadoway proved that titanium could be produced in one step. The elements taken from dirt to liquid metal of requisite purity, well below below the market price point. One-pot smelting without CO2 emissions and the by-product dioxins.