Hexavalent Chromium in Cement Manufacturing: Literature Review

With regard to chromium and health and safety aspects, the water-soluble compounds of chromium in cement are most relevant, specifically compounds of the form Cr (VI). Chromium in the cement can originate from: 1) raw materials or fuel, 2) magnesia-chrome kiln refractory brick, if used, 3) wear metal from raw mill grinding process, if chromium alloys are used, and 4) additions such as gypsum, pozzolans, ground granulated blast furnace slag, mineral components, and cement kiln dust. The cement process, specifically kiln conditions, can influence how much Cr (VI) will form. In the kiln, oxidizing atmosphere will play the largest role, with more oxygen in the burning zone leading to increased Cr (VI) formation. Alkali concentration is also of importance, since Cr (VI) in clinker is primarily in the form of chromates. In the finish mill, thermodynamically favorable conditions for oxidation to Cr (VI) exists, including high air sweep, moisture from gypsum dehydration, cooling water injection, and grinding aids, along with the high pH of the cement. Several materials have been used to reduce the level of soluble Cr (VI) formation. The most widely used material is ferrous sulfate; other materials include stannous sulfate, manganese sulfate, and stannous chloride. Some of these materials have limitations such as limited stability, limited supply, and possible influence on cement performance. In all cases, some form of dosing and mixing equipment is required.

• Availability:
  • Find a library where document is available. Order URL: http://www.cement.org/bookstore/profile.asp?itemid=SN2983
• Supplemental Notes:
  • Abstract reprinted with permission from Portland Cement Association
• Corporate Authors:

  Portland Cement Association

  5420 Old Orchard Road
  Skokie, IL  United States  60077
• Authors:
  • Hills, L
  • Johansen, V
• Publication Date: 2007

Language

• English

Media Info

• Media Type: Print
• Pagination: 16p

Subject/Index Terms

• TRT Terms: Alkali; Cement; Chromates; Chromium; Ferrous sulfide; Health; Kiln dust; Manufacturing; Oxidation; Oxygen; Safety; Solubility
• Uncontrolled Terms: Hexavalent
• Subject Areas: Highways; Materials; Safety and Human Factors; I32: Concrete;

Filing Info

• Accession Number: 01079997
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 25 2007 10:26AM