turbidity of sulphuric acid being produced

[vinay0003]

i work for zinc smelter plant and we obtain sulphuric acid as by product and it is produced by contact process but the problem here is that the sulphuric acid that is being produced is turbid can anyone state the reasons for this

 

[ash9144]

Most likely iron sulfate from contact with carbon steel or cast iron or nitrates given off by the smelting process.