Cementation

cementation

In geology, the hardening and welding of clastic sediments (those formed from preexisting rock fragments) by the precipitation of mineral matter in the pore spaces. It is the last stage in the formation of sedimentary rock. Many minerals may act as cements; the most common is silica (generally quartz), but calcite and other carbonates also occur, as do iron oxides, barite, anhydrite, zeolites, and clay minerals.

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cementation [‚sē‚men′tā·shən]

(chemistry)

The setting of a plastic material.

(engineering)

Plugging a cavity or drill hole with cement. Also known as dental work.

Consolidation of loose sediments or sand by injection of a chemical agent or binder.

(geology)

The precipitation of a binding material around minerals or grains in rocks.

(metallurgy)

High-temperature impregnation of a metal surface with another material.

Conversion of wrought iron into steel by packing layers of bars in charcoal sealed with clay and heating to 1000°C for 7-10 days.

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cementation

The setting of a cement.

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Cementation 

in construction, the consolidation of soils, rocks, and stone or concrete masonry by injecting a cement solution or suspension into voids, cracks, or pores. The process is used to strengthen the beddings of structures; to provide seepage barriers; and to waterproof rocks in tunnels, mine shafts, and stone and concrete masonry, as well as to reduce the porosity of such masonry.

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Cementation 

in nonferrous metallurgy, a hydrometallurgical process based on the displacement of the more electropositive metals from solutions of their compounds by less electropositive metals in the solid state. For example, the normal electrode potential of copper is +0.344 volts, and that of zinc is –0.762 volts; the difference between the potentials makes it possible to obtain the reaction Cu²⁺_solution + Zn_metal → Zn²⁺_solution + Cu_metal. The greater the difference in potentials, the lower the content of precipitated metal that will remain in the solution. Cementation is extensively used to remove impurities from solutions and to recover metals from solutions. The process can also be used to precipitate metals from molten slags.

REFERENCES

Plaksin, I. N., and D. M. Iukhtanov. Gidrometallurgiia. Moscow, 1949.
Maslenitskii, I. N., and L. V. Chugaev. Metallurgiia blagorodnykh melallov. Moscow, 1972.
Naboichenko, S. S., and V. I. Smirnov. Gidrometallurgiia medi. Moscow, 1974.