The solvent extraction circuit is housed in a separate building because the organic phase consists largely of kerosene which can burn. The overflow from counter-current decantation is clarified and pumped to solvent extraction which is described in the *.dwf image in the AutoDesk ExpressViewer in the pop-up flowsheet . Here the clarified overflow is mixed with a liquid mixture consisting of kerosene, isodecanol and amine. It is essential that the aqueous overflow sent to the solvent extraction circuit be clean and throughly filtered. Suspended solids in the aqueous overflow can cause fouling problems in the solvent extraction circuit. The uranium leaves the aqueous phase and transfers to the organic phase in a process called liquid ion exchange. In other mills, this process is accomplished through the use of ion exchange columns and solid ion exchange resins. The uranium is concentrated in this step. It is then further concentrated by transferring it from the organic phase to a second aqueous phase. The uranium is then precipitated from the aqueous phase with ammonia. This yields yellowcake slurry which is dried , barreled and shipped to the converter in the yellowcake area of the mill shown in the *.dwf image in the AutoDesk ExpressViewer in the pop-up flowsheet .