Aluminum-bearing minerals

Fig. 23.6. Calculated saturation indices (log Q/K) of aluminum-bearing minerals plotted versus temperature for a hot spring water from Gjogur, Hveravik, Iceland. Lines for most of the minerals are not labeled, due to space limitations. Sampling temperature is 72 °C and predicted equilibrium temperature (arrow) is about 80 °C. Clinoptilolite (zeolite) minerals are the most supersaturated minerals below this temperature and saponite (smectite clay) minerals are the most supersaturated above it.

Aluminum, the third most abundant element in the Earth s crust, is mined as bauxite, a mixure of gibbsite, boehmite, and diaspore. These ores occur dominantly in Cenozoic deposits formed by lateritic weathering of aluminous parent rock, which has broken down to leave a high proportion of aluminum-bearing minerals. These deposits are residual in nature, with the balance of the rock constituents removed by selective leaching. These deposits form most commonly in tropical and subtropical areas. 

Saturation Indices for aluminum-bearing minerals from minteqa2. 

Coal that is relatively rich in iron-bearing minerals (such as pyrite or siderite) has a low fusion temperature while coal relatively rich in aluminum-bearing minerals (such as kaolinite or illite) tends to have a high fusion temperature. If an electric generating or heating plant is designed to bum... 

The calculation predicts that a number of aluminum-bearing and iron-bearing minerals are supersaturated in the river water (Fig. 6.3). As discussed in the pre-... 

Emission spectroscopy analyses of the anthracites (Table IX) show that 90% of the ash of Pennsylvania anthracites is composed of silicon, aluminum, and iron-bearing minerals. 

Mixed Co-Al and Zn-Al hydroxide surface precipitates can also form on aluminum-bearing metal oxides and phyllosilicates (Towle et al., 1997 Thompson et al., 1999a,b Ford and Sparks, 2000). This is not surprising, as Co " ", Zir+, and NP+ all have radii similar to AP+, enhancing substitution in the mineral structure and formation of a coprecipitate. However, surface precipitates have not been observed with Pb2+, as Pb-+ is too large to substitute for AP+ in mineral structures (Sparks, 2002, 2005). 

The actinides (U, Th, Pu), alkaline earths (Be, Mg, Ca, Sr, Ba), lanthanides (elements La - Lu), Al, and the elements in groups 3b (Sc, Y), 4b (Ti, Zr, Hf), and 5b (V, Nb, Ta) of the periodic table are refractory lithophile elements. The refractory lithophiles are 5% of the total mass of the rock in solar composition material. Aluminum Al, calcium Ca, and titanium Ti are the three most abundant refractory lithophiles, and they form minerals that are the host phases for most of the less abundant refractory lithophile elements such as the actinides, lanthanides, and transition elements in group 5b of the periodic table. Some of the less abundant refractory lithophiles - the group 4b elements Zr, Hf, and the group 3b elements Y and Sc - condense as oxides before any Ca, Al, Ti-bearing minerals form [9], But the rest condense into the more abundant host phases. 

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