SHANGHAI, Feb 5 (SMM) – The operating rates of zinc smelters in January was up 1 percentage point from levels in December as output resumed at Shenzhen Zhongjin Lingnan Nonfemet, an SMM survey showed. For February, no new maintenance work has been planned so far but zinc production is set to be lower due to the Chinese New Year holiday. SMM expects the affected output would amount to over 20,000 mt.