Leaching potential of CKD when subjected to standardized leaching procedures and to a proposed conditioned CKD leaching procedure (CCLP)

Conference · Thu Dec 31 04:00:00 EST 1998

OSTI ID:347801

Wenzel, A; Stolzenburg, T ^[1]; Peters, C ^[2]

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1. RMT, Inc., Madison, WI (United States)
2. RMT, Inc., Okemos, MI (United States)

Cement kiln dust (CKD) can be highly leachable when subjected to the Toxicity Characteristic Leaching Procedure (TCLP), possibly resulting in more stringent environmental controls than are warranted for CKD disposal. Testing of moisture-conditioned CKD by the TCLP method is not representative of the typical environmental setting for disposed CKD. The TCLP uses an acid leaching solution that mimics conditions in a municipal landfill that has undergone decomposition. Little, if any, biological activity will occur in a CKD monofill. Furthermore, a standard TCLP does not account for the dramatic decrease in surface area that occurs with moisture-conditioned CKD. When CKD is conditioned with water and compacted it will set up as a hardened monolith. The Conditioned CKD Leaching Procedure (CCLP) was developed to better represent the environmental setting for moisture-conditioned CKD disposal in a monofill. A 100 g block of 28 day-old solidified CKD that achieves a minimum 100 psi compression strength and a maximum 10{sup {minus}5} cm/sec hydraulic conductivity is subjected to leaching either with Synthetic Precipitation Leaching Procedure (SPLP) leaching solution or site groundwater at a liquid to CKD ratio of 20:1. In addition, moisture-conditioned CKD block is suspended in a bottle containing the leaching solution and mixed with a magnetic stir bar for 18 {+-} 2 hours. The leachate is filtered and analyzed for constituents of concern. In general, leachate concentrations from a CCLP are markedly different than from a TCLP, which verifies that moisture-conditioned CKD leached with synthetic precipitation or site groundwater is much different than what is represented by a TCLP. Depending upon the test parameter of interest, the CCLP leached concentrations are one to two orders of magnitude lower than the other leaching procedures used.

• OSTI ID: 347801
• Report Number(s): CONF-9804112--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CEMENT INDUSTRY
COMPRESSION STRENGTH
DUSTS
HYDRAULIC CONDUCTIVITY
KILNS
LEACHING
MEASURING METHODS
MOISTURE
SOLIDIFICATION
WASTE DISPOSAL