Do I have to register a substance occuring in nature if I have to apply a process to extract this substance?

Substances occurring in nature are exempted from the duty to register in accordance with art. 2(7)(b) and Annex V, point 8 of REACH, as long as they are not chemically modified, not classified as dangerous in accordance with Directive 67/548/EEC, nor substances of very high concern, such as PBT or vPvB substances. If a process is applied to extract such a substance, it has to be verified whether the process applied is one of those listed in art. 3(39) of the REACH Regulation. If this is the case, the substance still qualifies as substance that occurs in nature that does not have to be registered.
The processes mentioned in art. 3(39) of REACH are manual, mechanical or gravitational processes, dissolution in water, flotation, extraction with water, steam distillation, heating solely to remove water and extraction from air. Please note that extraction with solvents other than water, like e.g. hexane or ethanol, are not covered by art. 3(39) of REACH. Substances which are extracted with these solvents do not qualify as a substance that occurs in nature and cannot be exempted from registration on the basis of Annex V, point 8 of REACH.
Lavender oil, for example, is extracted from flowers of certain species of lavender (which occur in nature) by means of steam distillation. The subsequent spontaneous separation of oil and water allows an easy isolation of the lavender oil. As this extraction process is mentioned in art. 3(39) of REACH, the lavender oil can be regarded as a substance that occurs in nature.
On the contrary, chrysanthemum oil, for example, which is extracted from chrysanthemum blossoms and leaves (which occur in nature) with a solvent mixture of water and ethanol (1:10), cannot be regarded as a substance that occurs in nature.
In general, it is important to remember that it is up to the manufacturer to assess the process applied and to determine if the definition of art. 3(39) of REACH is applicable or not.

Do I have to register alloys?

The REACH Regulation refers to alloys as “special mixtures” (Recital (31), Annex I (0.11.), as amended by Regulation (EC) No 1272/2008). Therefore, an alloy is to be treated in the same way as other mixtures under REACH, which means that the alloy as such is not subject to registration but the alloying elements (e.g. metals), irrespectively of the production process of the alloy are. However, components which are not important for the properties of the alloy should be considered as impurities (i.e. they are part of a substance in the mixture) and therefore need not be registered separately. Please note that intermetallic compounds are often wrongly regarded as alloys, although they have a well defined stoichiometry. Such substances are listed in EINECS (e.g. “aluminium, compound with iron (1:1)”, “iron, compound with titanium (2:1)”, etc.) and cannot be regarded as mixtures, therefore these intermetallic compounds have to be registered as such. This means that e.g. separate (pre-)registrations of the substances Al and Fe do not cover the substances “aluminium, compound with iron (1:1)” or “aluminium, compound with iron (1:3)”. For each intermetallic compound with a different metal ratio a separate (pre-)registration is required.

How do I calculate the tonnage?

Each registrant has to calculate the yearly tonnage for the registration dossier. The yearly tonnage is calculated as the volume per manufacturer/importer per calendar year, unless stated otherwise. For phase-in substances that have been imported or manufactured for at the least three consecutive years, quantities are calculated on the basis of the average production or import volumes for the three preceding calendar years (Article 3 (30) of the REACH Regulation).