Guillaume Daniel Delprat

Guillaume Daniel Delprat CBE (1 September 1856 – 15 March 1937) was a Dutch-Australian metallurgist, mining engineer, and businessman. He was a developer of the froth flotation process for separating minerals.

Delprat was born in Delft, the Netherlands, son of Major General Felix Albert Theodore Delprat (1812–1888), later minister of war, and his wife Elisabeth Francina, née van Santen Kolff.

Delprat attended a high school in Amsterdam and later became an apprentice engineer on the Tay Bridge in Scotland. He attended science classes in Newport-on-Tay and learned calculus from his father by post. On returning to the Netherlands, he is said to have acted as assistant to Johannes Diderik van der Waals, physics professor at the University of Amsterdam. From 1879 to 1882, Delprat worked in Spain at the Tharsis Sulphur and Copper Mines.

In 1898, chairman E. N. Wigg of Broken Hill Proprietary invited Delprat to Australia to become Assistant General Manager of BHP. He moved there with his wife and children. On 1 April 1899, he was promoted to General Manager, a position he held until 1921. At BHP, he pioneered the froth flotation process for refining sulphide ore. Delprat foresaw the exhaustion of BHP's mine at Broken Hill, and pushed for moving the company's smelters to Port Pirie; also construction of the Iron Knob railways. He shifted BHP from silver and lead mining to zinc and sulphur production. These moves were the basis of BHP's later success.

Delprat also pushed construction of the BHP steelworks at Newcastle, New South Wales. The contract was signed on 24 September 1912 and the steelworks were opened by Governor-General Novar on 2 June 1915. For Delprat's visionary judgement in the project he was made a CBE.

In 1935 Delprat was the first recipient of the medal of the Australasian Institute of Mining and Metallurgy.