Olivine sand

Olivine sands are a mineral group which includes forsterite, fayalite and others. The characteristics of olivine sands are as follows  

The basic pH makes this type of sand not suitable for use with acid catalysed binder systems. 

Olivine sand is produced by crushing natural rocks, which explains its diverse characteristics. It is usually used for moulding and core-making in manganese steel casting. The presence of manganese prohibits the presence of silica as these two components react to give a very fusible compound. The reported purchase price in Spain is EUR 130/tonne (2002). 

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In FBs, tars are generated, but these can be partially decomposed to gas using in situ catalysts such as dolomite70 and treated olivine sand.46 The tars can further be cracked or reformed downstream in separate beds yielding additional syngas, and thus, hydrogen (see Section 6.3.4). A new development is the combination of ceramic gas filtration and catalytic tar cracking see Heidenreich and Nacken.71... 

Bed material MgO Silver- sand Silver- sand Dolo- mite Silver- sand Olivine sand Olivine sand... 

This paper compares the outlet dimensions predicted by the Jenike silo design method [2], with those measured experimentally, in a plane flow silo test facility. These results represent a small portion of an experimental program outlined in [9], which involved the technique of laser ranging for the measurement of critical cohesive arch profiles. These experimental arching tests, and failure property measurements have been conducted with three cohesive bulk solids, namely a fly ash, hydiated lime, and olivine sand (mixed with a glycerol solution to provide cohesion). 

The calculated failure functions for fly ash, hydrated lime and olivine sand which were used for outlet design, are illustrated in Fig. 2. A linear failure function was assumed, and least sum of squares regression was used to fit the measured data points. For olivine sand, individual failure functions were calculated from the strength measurements of the respective shear cells. For fly ash, and hydrated lime, as indicated by the correlation coefficients (in... 

Fig. 2. Failure functions for fly ash, hydrated lime, and olivine sand.

A comparison of the experimentally determined critical arch spans /outlet widths and the critical outlet widths calculated from the Jenike method [2] are given in table 2, for fly ash, hydrated lime and olivine sand. In table 2 at filling represents the measured maximum arch span which occurred prior to sustained flow of the stored bulk solid. The intervals on the predicted outlet widths are at the 95% confidence limit determined from statistical analysis of the failure function data. The recommended mass flow design lines [2] correspond with hopper half angles of 37, 28, and 30 degrees respectively for fly ash, hydrated lime and olivine sand. 

For the fly ash the Jenike design criterion estimates that their is no minimum critical outlet width for flow, which compares well, with experimental observations, which found the instantaneous outlet width to be below the minimum obtainable with the test silo. For the hydrated lime and olivine sand, the actual critical outlet widths at emptying were of a similar size to that of fly ash, but the Jenike method over predicted this by almost an order of magnitude. 

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