Questions regarding the zinc concentrate acid production project
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I encountered a project to produce sulfuric acid from zinc concentrate, with an annual output of 60,000 tons of sulfuric acid; this company plans to implement a project for generating electricity using the waste heat from the sulfuric acid production process. Is this company too small in scale, and is it at risk of being phased out? Is it still meaningful to support this company in using the waste heat from sulfuric acid production for power generation? Thank you
The annual production capacity for acids is only 60,000 tons, while that for zinc is only 30,000 tons; zinc smelting projects with a production capacity of less than 50,000 tons do not comply with **’s industrial policies.
60,000 tons of zinc, with a sulfuric acid production of 100,000 tons – it’s a shame that this heat isn’t utilized! For zinc electrolysis plants, it is ideal to use a waste heat boiler to generate saturated steam at 2.45 MPa; after temperature and pressure reduction, this steam can be used for heating the solution in the high-temperature leaching process as well as for the second high-temperature purification step. There is no need to operate boilers, as the steam supply can be balanced in this way. There is then no need to generate electricity; of course, power generation devices are only considered when steam is useless. Alternatively, generate electricity first (with a 3.82 MPa residual boiler) and then use the low-pressure steam for zinc electrolysis.
I think that if one were to pursue a waste heat power generation project, the investment would be quite high, and there would also be relatively little heat available! I believe that the high-temperature flue gas at around 1050°C at the outlet of the boiling furnace, as well as the heat removed from the boiling layer, can be recovered using a naturally circulating water-tube medium-pressure waste heat boiler. The generated medium-pressure boiler steam is sent to the conversion section to drive the SO2 blower. To ensure steam quality, the water entering the medium-pressure waste heat boiler is demineralized water. The system is equipped with water treatment facilities to ensure that the conductivity of the water supplied to the boiler is ≤5 mS/cm, meeting the requirements for water quality in power station boilers.
It’s hard to say whether something will be phased out; whether it will be eliminated depends mainly on its economic viability, as well as on whether it meets environmental standards For 60,000 tons, waste heat power generation is possible, but **according to the latest policies, sulfuric acid plants with a capacity of less than 100,000 tons are not allowed to be built.
In terms of industry entry policies, the lead-zinc industry requires 109 square meters per boiling furnace, which corresponds to a sulfuric acid production capacity of 200,000 tons per year; but how many companies in China can meet this requirement? As for waste heat recovery, I personally think it is very necessary, because the zinc production process requires steam, and when it comes to power generation, it seems that the costs are not justified – the benefits do not outweigh the costs. My personal opinion: handshake
May I ask which industrial policy document mentions the 60,000 tons mentioned upstairs?