wax glossary

Additive: a substance added to petroleum products to get desirable property, e.g. Polymer may be added to a petroleum wax to increase tackiness, or added to food grade to prevent oxidation in storage.

Alkanes: hydrocarbon which has the general Formula Cnttzn+z, also called paraffin.

Aromatics: hydrocarbons with an absorbing ring structure like Benzene.

ASTM: American Society for Testing Materials, an organization which sets standards for the testing of industrial products.

Cloud Point: the temperature at which the first signs of wax precipitation appear in an oil.

Color: the color of most waxes is measured only while molten, because occluded air and surface finish may cause the color of solid samples of the wax to vary significantly.

Crystallization: in de-waxing operations, formation of a solid (wax), prior to separation by filtration.

De-waxing: the separation process used to refine waxy gas oils into wax-free oil. Solvent de-waxing, in which a mixture of feed and solvent is chilled to crystallize the waxy portion for removal by filter or centrifuge, produces low-pour lube base stocks and slack wax. The slack wax may be deoiled to reduce oil content and produce fully-refined wax. Alternate technologies for dewaxing include wax hydro isomerization, in which wax molecules are branched in a catalytic reaction and converted into high VI lubricants, and catalytic de-waxing, in which wax molecules are destroyed and become lighter, fuels products.

De-oiling: the separation process used to refine slack wax into finished petroleum waxes. The predominant process operates by chilling a mixture of feed and solvent to crystallize the wax, then separating the wax from the oil and solvent mix by filter or centrifuge. Solvent deoiling may be conducted as an integral part of a dewaxing/deoiling plant or operate as an independent plant. Alternate processes for deoiling include "sweating" the oil from the wax and fractional crystallization.

Melt Point: the temperature at which a material changes phase from solid to liquid. Petroleum waxes usually do not melt at sharply defined temperatures because they are mixtures of hydrocarbons with different melting points. Paraffin waxes are relatively simple mixtures and can have narrower melting ranges than micro crystalline waxes and petro latums which are more complex in composition and melting behavior. The congealing point (ASTM D938) is the temperature at which a melted wax ceases to flow, and is more consistent than melting points for some waxes.

Micro crystalline Wax: hydrocarbons of molecular weight higher than 450 and less than 800.

Oil Content: the amount of residual oil left in petroleum wax after refining. Oil content is determined as that percentage of wax soluble in methyl ethyl ketone at -31.7°C. The method is applicable to waxes containing not more than 15% oil. A similar method, D3235 Test for Solvent Extra ctables in Petroleum Wax uses a 1:1 mixture of methyl ethyl ketone and toluene and may be used on waxes having levels of extrac tables as high as 50%.

Paraffins: open chain, saturated hydrocarbons, e.g. Hexane, iso octane, etc.

Paraffin Wax: hydrocarbons of molecular weight higher than 350 and lower than 520 which are solid at room temperature.

Paraffin Wax - Fully Refined: paraffin wax that has been refined to a residual oil content no more than 1%, usually lower than 0.5% and generally meeting FDA food grade standards.

Penetration: the standard test for hardness of wax is ASTM D1321, which measures the depth in tenths of a millimeter that a needle of certain configuration, under a given weight, penetrates the surface of a wax at a given temperature. A series of penetrations measured at different temperatures, rather than a single temperature is preferred. Penetration of softer waxes and petrolatum may be measured using a cone rather than a needle.

Resins: any of a class of solid or semi-solid organic products of natural or synthetic origin with no definite melting point. Generally of higher molecular weight, most resins are polymers.

Scale Wax: a semi-refined paraffin wax with an oil content of 1 - 3%

Slack Wax: generic term for the mixture of wax and oil recovered in a de-waxing process; may contain 2 - 35% oil. Typical dispositions are to further process for finished wax, to process for fuels or to sell into certain end-use markets.

Viscosity: ASTM D88 is used to measure the time in seconds required for a specified quantity of wax at a specified temperature to flow by gravity through an orifice of specified dimensions.

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