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A first stage in the manufacture of superphosphate is to produce sulfuric acid. Elemental sulfur, from Canada, is treated with acid. The reaction generates heat, and the resulting sulfuric acid must be cooled. Shown here are early cooling tanks. The acid is mixed with rock phosphate to produce superphosphate and the hot, sticky product is then dried.
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Archives New Zealand - Te Rua Mahara o te Kāwanatanga
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