Complex sentence: Zhaoyuan, a Shandong provincial city of a population of 580,000 has more than 60 gold mines operating in the hills around the city that annually mine about 15% of China's total gold-the most in the country.
Split into simpler sentences: Zhaoyuan, a Shandong provincial city of a population of 580,000, has more than 60 gold mines operating in the hills around the city. They annuall produce about 15% of China's total gold-the most in the country.