Recovery and Enrichment of Aqueous Phosphate From the Slag Released by a Chemical Factory

Abstract

: The elution behaviors of phosphate from the slag released by a chemical factory using various eluates were examined. Since this slag was covered with organic species, two pretreatment methods for the slag -one the calcination of the slag and the other the trituration of the slag -were employed to strip away the organic species from the slag. Since the elution rate from the pre-triturated slag was evidently greater than that from the pre-calcined slag, the elution behavior of the former was mainly examined in the present study. For the efficient elution of phosphate from the slag, the use of 1M HNO 3 as an eluate and 30 min of trituration time were suitable. Unfortunately, together with the elution of phosphate from the slag, some cationic species were simultaneously eluted. In the present study, the removal behavior of iron cation, which was a main contaminant in the slag, using calcium hydroxyapatite (CaHAp) was also examined. Even when the solution obtained by the elution of the slag was employed for the removal of Fe 3+ using CaHAp, the Fe 3+ could be favorably removed from the solution. Results from the present study suggests that unused phosphate in slag is a potential source of raw material for rare phosphorus.

Phosphorus Recovery From Sewage-Sludge Molten Slag Using a Combination of Acid-Dissolution, Alkali-Precipitation, and Ion-Exchange

“…[2][3][4][5][6][7]11,12 Figure 2 shows the effect of the treatment time for the elution of the sewage sludge molten slag using 0.5 M HNO3, although treatment times of less than 0.2-0.5 h are reported as suitable for the elution of phosphorus from various phosphorus-containing unused resources. [2][3][4][5][6][7]11,12 However, as shown in Figure 2, when using sewage-sludge molten slag, a longer treatment time resulted in a slight increase in the elution of phosphorous from the slag, while the elution of calcium as a second main element seemed insensitive to the concentration of HNO3. Since it seemed advantageous to avoid a long elution operation, 0.5 M nitric acid was used and the treatment time was set to 1.0 h for obtaining Filtrate ().…”

Recovery of Calcium Phosphates from Composted Chicken Manure

“…However, it is generally accepted that phosphate rock as a raw material for phosphorus will disappear in the near future (Abelson, 1999). Therefore, our laboratory has reported on the recovery of phosphate from unused resources such as from rivers by using boehmite as an adsorbent, from dephosphorization slag, chemical slag, and used fluorescence tubes using acidic solutions as eluates (Sugiyama et al, 2011(Sugiyama et al, , 2012(Sugiyama et al, , 2014(Sugiyama et al, , 2015. In particular, a phosphate-containing solid was successfully precipitated from the nitric acid extract of dephosphorization slag, simply by adjusting the solution pH to 7.0 (Sugiyama et al, 2014).…”

“…To confirm the most favorable dissolution of Ca 2+ and PO 4 3from the manure, we followed a procedure established in our previous papers (Sugiyama et al, 2012) by first examination of the elution behavior of composted chicken manure using aqueous HNO 3 , HCl and H 2 SO 4 to form an aqueous complex mixture containing calcium and phosphate. Aqueous HNO 3 was the most suitable eluate, so we examined the separation of calcium phosphates as a precipitation from the nitric acid extract via pH-adjustment using aq.…”

Recovery of the Phosphorus from the Nitric Acid Extract of Powder Collected in a Bag Filter during the Recycling of Used Fluorescence Tubes

“…Extraction of phosphate from iron ore using an acidic solution has also been reported (Zhang and Muhammed, 1989;Patrick and Lovel, 2001). In our laboratory, we have used slag released from the processing of steel (Sugiyama et al, 2011(Sugiyama et al, , 2014 and that from chemical factories (Sugiyama et al, 2012) as new sources of phosphorus. We have been able to dissolve aqueous phosphate from both types of slag using nitric acid, while a phosphatecontaining solid could be precipitated from the nitric acid extract of the slag released from steel processing, simply by adjusting the solution pH to 7.0 (Sugiyama et al, 2014).…”