Abstract SYMPHOS 2011

52
Marten WALTERS
KEMWorks Technology, Inc.,
Lakeland/USA
Historically phosphoric acid has been made from phosphate rock by reaction with sulfuric acid (the Wet Process) or
a high temperature electric furnace carbon reduction (the Electric Furnace Process). Economic concerns led to the
closure of most Electric Furnaces and the Wet Process came to dominate.
In 1960, Lapple demonstrated that a rotary kiln had the ability to replace the energy supplied by electricity in the
Electric Furnace Process with energy generated by carbon. This concept was advanced by many researchers but all
failed because of melting problems that Dr. Hard later overcame in 1981. The process employs a rotary kiln reactor
and was proven in pilot plant testing.
In 2003, Dr. Joseph A. Megy restarted R&D on the Hard Process, and made additional discoveries that led to the
Improved Hard Process (IHP), and today design of a semi-commercial demonstration plant is in progress.
The IHP is claimed to be able to process low-grade phosphates and to produce phosphoric acid at lower cost than by
the Wet Process. This paper presents the results of a Third-Party review of technical aspects of the process, suitable
phosphate reserves, and environmental issues.
John Gobbitt
Yara Belgium S.A. Brussels,
BELGIUM
A REVIEW OF THE IMPROVED HARD PROCESS
PH-O-01
YARA HEMIHYDRATE (HH) AND HEMIDIHYDRATE (HDH) PROCESSES
FOR PHOSPHORIC ACID PRODUCTION
PH-O-02
Yara own, operate and license fertilizer plants and technologies throughout the world. Phosphoric acid production
is an important part of the Yara licensing portfolio. Formerly known as Hydro Agri and prior to that, Fisons, we have
successfully designed and commissioned several world scale hemihydrate and hemidihydrate process phosphoric
acid plants over the course of the last forty years. The largest of these plants was the IPL (formerly WMC) HH process
phosphoric acid plant in Queensland, Australia. This single line grass roots 1500 tpd P2O5 plant has now been
successfully operating for over ten years.
The HH and HDH processes are characterised by producing high strength phosphoric acid directly from the
hemihydrate filters; either negating or significantly reducing the degree of acid concentration required for
downstream processes. The HH process is therefore energy efficient, simple to operate and as most of the aluminium
reports to the solid phase, the phosphoric acid is of high quality. The HDH process is a two stage process whereby
the hemihydrate produced in the energy efficient first stage is transformed to dihydrate in the second stage and
the liberated P2O5 losses present in the hemihydrate produced in the first stage are recovered, resulting in a very
high P2O5 recovery efficiency.
This paper focuses on the hemihydrate technologies developed by Yara (as Fisons Fertilizers) and looks forward to
the next major hemihydrate complex at Ras As Zwar in the Kingdom of Saudi Arabia where Yara are providing the
license for Ma’aden Phosphate Company (MPC) to operate three independent phosphoric acid trains, each with a
capacity of 1460 tpd P2O5.