Characterization of Sludge Deposits from Refineries and Gas Plants: Prerequisite Results Requirements to Facilitate Chemical Cleaning of the Particular Equipment

Table 1

Summary of the identified phases of the inorganic materials (i.e., the insoluble part or nonhydrocarbon) separated from the hydrocarbon (dichloromethane soluble part) of the sludge deposits, and its nature [1].

The Identified Phases	Nature of the Corrosion and Scale Products
Magnetite (Fe3O4); Lepidocrocite (FeOOH); Goethite (FeOOH); Akaganeite (FeOOH)	Iron Oxide Corrosion Product: (i) At a high temperature magnetite corrosion products it will coat the iron/steel to prevent oxygen to reach underlying metal. Mostly, at low temperature, lepidocrocite formed and with time it transformed into most stable goethite. Akaganeite formed in marine environments.
Gregite (Fe3S4); Pyrite (FeS2); Marcasite (FeS2); Mackinawite (FeS0.9); Pyrrhotite (Fe7S8)	Iron Sulfide Corrosion Products: (i) Pyrophoric iron sulfide (pyrrhotite-FeS) results from the corrosive action of sulfur or sulfur compounds (H2S) on the iron (steel) and moisture.
Iron Chloride (FeCl3); Iron Chloride Hydrate (FeCl2-4H2O)	Chloride corrosion products
Calcite (CaCO3); Aragonite (CaCO3); Siderite (FeCO3)	Carbonate scale
Basanite (CaSO4. 2H2O); Anhydrite (CaSO4); Gypsum (CaSO4. 2H2O)	Sulfate scale
Quartz (SiO2); Albite (NaAlSi3O8); Microcline (KAlSi3O8); Cristoballite (SiO2)	Formation material: (i) Normally found in the sandstone or sand
Illite (K.5(AlFeMg)3(SiAl)4O10(OH)2)	Clay minerals normally found with sandstone
Ettringite (Ca6Al2(SO4)3(OH)12)	Cementing material
Barite (BaSO4)	Drilling mud
Aluminum Oxide (Al2O3)	Normally from catalyst
Sulfur (S)
Sodium Iron Oxide (NaFeO2)