BEIJING—China’s factory gate inflation hit a 13-year high in August driven by roaring raw materials prices despite Beijing’s attempts to cool them, putting more pressure on manufacturers in the world’s second-largest economy. The producer price index (PPI) rose 9.5 percent from a year earlier in August, the National Bureau of Statistics (NBS) said on Thursday, faster than the 9.0 percent increase tipped in a Reuters poll and the 9.0 percent reported in July. That was the fastest pace since August 2008. China’s economy has recovered strongly from last year’s coronavirus slump but has been losing steam recently due to domestic COVID-19 outbreaks, high raw material prices, tighter property curbs, and a campaign to reduce carbon emissions. Commodity prices have been on a tear in recent months, hurting the bottom lines of many mid—and downstream factories. China’s coal prices soared to a record high on Tuesday over supply concerns as major …