Penniman process

The Penniman process is probably the most widely used production method for yellow iron oxide pigments [3.26], [3.27], This method considerably reduces the quantity of neutral salts formed as byproducts. The raw materials are iron(II) sulfate, sodium hydroxide solution, and scrap iron. If the sulfate contains appreciable quantities of salt impurities, these must be removed by partial precipitation. The iron must be free of alloying components. The process usually consists of two stages (Fig. 23, Route B). 

Under suitable conditions the Penniman process can also be used to produce reds directly. The residual scrap iron and coarse particles are removed from the pigment, which is then dried [3.35] and ground using disintegrators or jet mills. These pigments have unsurpassed softness. They usually have purer color than the harder red pigments produced by calcination. 

The Penniman process using iron(II) sulfate, sodium hydroxide solution, and scrap iron... 

Production. Three commercial processes are used for the production of iron yellows the Penniman-Zoph process, the precipitation process, and the Faux process. 

The Penniman-Zoph process involves the preparation of seeds or nucleating particles by the alkaU precipitation of ferrous sulfate. The reaction is carried out at alow temperature using an excess of ferrous ions. The hydroxide is then oxidized to the seeds of hydrated ferric oxide ... 

Pcnniman A process for oxidizing petroleum, or its distillates, to mixtures of acids, phenols, and aldehydes. Powdered coal or coke is added to the petroleum, and air is passed through under high temperature and pressure. Invented by W. B. D. Penniman in 1925. 

Penniman-Zoph A process for making a yellow iron oxide pigment. Hydrated ferric oxide seed is added to a solution of ferrous sulfate and the suspension circulated over scrap iron, with air being passed through. Hydrated ferric oxide deposits on the seed crystals, giving a finely divided, yellow pigment ... 

Penniman-Zoph process, 19 400 Penning cold-cathode ionization gauges,... 

Figure 23. Production of yellow iron oxide by the precipitation (A) and Penniman (B) processes a) Tank b) Pigment reactor c) Seed reactor d) Pigment reactor with scrap basket e) Filter f) Dryer g) Mill...

Fig. 3.2 Production of yellow iron oxide by the precipitation (left) and Penniman (right) process, a) seeding tank, b) precipitation pigment reactor, c) Penniman pigment reactor with scrap basket, d) filter, e) dryer, f) mill.

Particles can also be grown by adding scrap iron and oxidizing it with air without the consumption of any other chemicals (Penniman-Zoph process). 

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