---
kind: "section"
citation: "40 C.F.R. § 61.51"
title: "40"
number: "61.51"
heading: "Definitions."
url: "https://uscodex.org/cfr/40/61.51"
---

# §61.51. Definitions.


Terms used in this subpart are defined in the act, in subpart A of this part, or in this section as follows:

- (a) Mercury means the element mercury, excluding any associated elements, and includes mercury in particulates, vapors, aerosols, and compounds.
- (b) Mercury ore means a mineral mined specifically for its mercury content.
- (c) Mercury ore processing facility means a facility processing mercury ore to obtain mercury.
- (d) **Condenser stack gases—** mean the gaseous effluent evolved from the stack of processes utilizing heat to extract mercury metal from mercury ore.
- (e) Mercury chlor-alkali cell means a device which is basically composed of an electrolyzer section and a denuder (decomposer) section and utilizes mercury to produce chlorine gas, hydrogen gas, and alkali metal hydroxide.
- (f) Mercury chlor-alkali electrolyzer means an electrolytic device which is part of a mercury chlor-alkali cell and utilizes a flowing mercury cathode to produce chlorine gas and alkali metal amalgam.
- (g) Denuder means a horizontal or vertical container which is part of a mercury chlor-alkali cell and in which water and alkali metal amalgam are converted to alkali metal hydroxide, mercury, and hydrogen gas in a short-circuited, electrolytic reaction.
- (h) Hydrogen gas stream means a hydrogen stream formed in the chlor-alkali cell denuder.
- (i) End box means a container(s) located on one or both ends of a mercury chlor-alkali electrolyzer which serves as a connection between the electrolyzer and denuder for rich and stripped amalgam.
- (j) End box ventilation system means a ventilation system which collects mercury emissions from the end-boxes, the mercury pump sumps, and their water collection systems.
- (k) Cell room means a structure(s) housing one or more mercury electrolytic chlor-alkali cells.
- (l) Sludge means sludge produced by a treatment plant that processes municipal or industrial waste waters.
- (m) Sludge dryer means a device used to reduce the moisture content of sludge by heating to temperatures above 65 °C (ca. 150 °F) directly with combustion gases.

## Notes

### Amendments

[38 FR 8826, Apr. 6, 1973, as amended at 40 FR 48302, Oct. 14, 1975]

### Authority

Authority: 42 U.S.C. 7401 et seq.

### Source

Source: 38 FR 8826, Apr. 6, 1973, unless otherwise noted.

### Amendments

[38 FR 8826, Apr. 6, 1973, as amended at 40 FR 48302, Oct. 14, 1975]