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i

Evaluation of Humidity Cell Parameters Their Effect on Precision and Repeatability

Public Domain


Details

  • Personal Author:
  • Description:
    The prediction of acid rock drainage (ARD) from mineral processing tailings is an inexact procedure, and variations in results are common. The U.S. Bureau of Mines has evaluated the major parameters associated with humidity cell tests to determine their effect on the test's precision and repeatability. A set of 44-week tests on 50-yr-old tailings was performed with temperature control and changes in effluent volume and airflow. The temperature was maintained at 30 degrees +/- 1 degree C. The airflow across the sample surface during the dry and wet air portions of the cycle was set at either 250 or 500 mL/min. The leach solution volume was varied to recover an effluent equivalent to up to 50% of the sample mass. The responses monitored were moisture removed during air addition, effluent volume, and acid in effluent (the amount of base required to titrate to pH 6), and total soluble sulfur. Changes in airflow and effluent volume affected the amounts of sulfate and acid reporting to effluent. Increased airflow resulted in more moisture removal and increased acid generation. As the effluent volume was varied, a maximum for acid generation was observed at 100 mL/325 g of sample. The data indicate that consistency in airflow and ratio of effluent volume to sample mass may improve the precision of the humidity cell test data. In addition, titration of the effluent provided a better measure of the acid content of the effluent than did pH monitoring. Precise and repeatable data should make the comparison of humidity cell data and ARD prediction between samples and testing facilities more reliable. [Description provided by NIOSH]
  • Subjects:
  • Keywords:
  • Series:
    Mining Publications
  • Publisher:
    U.S. Department of the Interior, Bureau of Mines
  • Document Type:
    Text
  • Genre:
    Proceedings
  • Place as Subject:
  • CIO:
    National Institute for Occupational Safety and Health (NIOSH)
  • Division:
    RERC - Reno Research Center
  • Topic:
    Workplace Safety & Health
  • Location:
    North America
  • Pages in Document:
    326-333
  • Volume:
    2
  • NIOSHTIC Number:
    nn:20050435
  • Citation:
    Proceedings of the International Land Reclamation and Mine Drainage Conference and Third International Conference on the Abatement of Acidic Drainage April 24-29, 1994, Pittsburgh, Pennsylvania. Pittsburgh, PA: United States Department of the Interior, Bureau of Mines, Special Publication SP 06B-94, 1994 Apr; 2:326-333
  • Federal Fiscal Year:
    1994
  • Peer Reviewed:
    False
  • Source Full Name:
    Proceedings of the International Land Reclamation and Mine Drainage Conference and Third International Conference on the Abatement of Acidic Drainage April 24-29, 1994, Pittsburgh, Pennsylvania
  • Collection(s):
  • Main Document Checksum:
    urn:sha-512:82d18818704d2735127372b0ba2a27b8c517fa5d38baab7610326550cee449797c281860c3a8186f48f360b7eb61a51173f876c62afbe7b3418eb368109cfe75
  • Download URL:
  • File Type:
    Filetype[PDF - 260.08 KB ]
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