In 1740 the general concession, lasting thirty years, was assigned to the British Charles Brander, to the baron Karl von Holtzendorf and to the Swedish consule in Cagliari Karl Gustav Mandel. According to the agreement, the concessionaries should pay to the King's Treasury 12% of the extracted galena and 2% of the silver for the first 4 years, 5% for the following 6 years and 10% for the remaining 20 years. The obligatory taxes had to be paid at the dispatch for exported commodities and within six months for those that had been sold into the island. The new company, boosted especially by Mandel, introduced some technological innovations, among which the use of the explosive during mining operations. Handwoks skilled in mining industry were brought to Sardinia especially from Germany. Mandel also built by Villacidro a large lead foundry. He was though accused by the Real Intendance of neglecting the exploration of new mines confining himself to exploit the existing ones. An enquiry was also opened for alleged fiscal illegalities that led in 1758 to the repeal of the concession of Mandel.