Abstract: A system for recovering rare earth elements from coal ash includes a leaching reactor, an ash dryer downstream of the leaching reactor, and a roaster downstream of the ash dryer that is cooperatively connected to both the leaching reactor and the ash dryer. Coal ash is mixed with an acid stream such that rare earth elements present in the coal ash are dissolved in the acid stream, thereby creating (i) a leachate containing the rare earth elements and (ii) leached ash. The leachate is heated to obtain acid vapor and an acid-soluble rare earth concentrate. Mixing of the coal ash with the acid stream can occur in a leaching reactor and heating of the leachate can occur in a roaster. The acid-soluble rare earth concentrate can be fed to a hydrometallurgical process to separate and purify the rare earth elements.

Abstract: Methods of recovering rare earth elements, vanadium, cobalt, or lithium from coal are described. The coal is dissolved in a first solvent to dissolve organic material in the coal and create a slurry containing coal ash enriched with rare earth elements, vanadium, cobalt, or lithium. The enriched coal ash is separated from the first solvent. Residual organic material is removed from the coal ash. The rare earth elements, vanadium, cobalt, or lithium can then be recovered from the coal ash. The coal ash is mixed with an acid stream that dissolves the rare earth elements, thereby creating (i) a leachate containing the rare earth elements and (ii) leached ash. The leachate is heated to obtain acid vapor and an acid-soluble rare earth concentrate. The acid-soluble rare earth concentrate can be fed to a hydrometallurgical process to separate and purify the rare earth elements.

Abstract: A method of making a zeolite comprises: adding a zeolite seed to a leach solution containing silicon and aluminum; and heating the leach solution to obtain the zeolite. The leach solution can be made by mixing coal ash with a basic stream, thereby creating (i) a leach solution containing silicon and aluminum, and (ii) leached ash; and separating the leach solution from the leached ash.

Abstract: A system for recovering rare earth elements from coal ash includes a leaching reactor, an ash dryer downstream of the leaching reactor, and a roaster downstream of the ash dryer that is cooperatively connected to both the leaching reactor and the ash dryer. Coal ash is mixed with an acid stream such that rare earth elements present in the coal ash are dissolved in the acid stream, thereby creating (i) a leachate containing the rare earth elements and (ii) leached ash. The leachate is heated to obtain acid vapor and an acid-soluble rare earth concentrate. Mixing of the coal ash with the acid stream can occur in a leaching reactor and heating of the leachate can occur in a roaster. The acid-soluble rare earth concentrate can be fed to a hydrometallurgical process to separate and purify the rare earth elements.

Abstract: Methods of recovering rare earth elements, vanadium, cobalt, or lithium from coal are described. The coal is dissolved in a first solvent to dissolve organic material in the coal and create a slurry containing coal ash enriched with rare earth elements, vanadium, cobalt, or lithium. The enriched coal ash is separated from the first solvent. Residual organic material is removed from the coal ash. The rare earth elements, vanadium, cobalt, or lithium can then be recovered from the coal ash. The coal ash is mixed with an acid stream that dissolves the rare earth elements, thereby creating (i) a leachate containing the rare earth elements and (ii) leached ash. The leachate is heated to obtain acid vapor and an acid-soluble rare earth concentrate. The acid-soluble rare earth concentrate can be fed to a hydrometallurgical process to separate and purify the rare earth elements.

Abstract: A system for recovering rare earth elements from coal ash includes a leaching reactor, an ash dryer downstream of the leaching reactor, and a roaster downstream of the ash dryer that is cooperatively connected to both the leaching reactor and the ash dryer. Coal ash is mixed with an acid stream such that rare earth elements present in the coal ash are dissolved in the acid stream, thereby creating (i) a leachate containing the rare earth elements and (ii) leached ash. The leachate is heated to obtain acid vapor and an acid-soluble rare earth concentrate. Mixing of the coal ash with the acid stream can occur in a leaching reactor and heating of the leachate can occur in a roaster. The acid-soluble rare earth concentrate can be fed to a hydrometallurgical process to separate and purify the rare earth elements.

Abstract: A method of making a zeolite comprises: adding a zeolite seed to a leach solution containing silicon and aluminum; and heating the leach solution to obtain the zeolite. The leach solution can be made by mixing coal ash with a basic stream, thereby creating (i) a leach solution containing silicon and aluminum, and (ii) leached ash; and separating the leach solution from the leached ash.

Abstract: A system for recovering rare earth elements from coal ash includes a leaching reactor, an ash dryer downstream of the leaching reactor, and a roaster downstream of the ash dryer that is cooperatively connected to both the leaching reactor and the ash dryer. Coal ash is mixed with an acid stream such that rare earth elements present in the coal ash are dissolved in the acid stream, thereby creating (i) a leachate containing the rare earth elements and (ii) leached ash. The leachate is heated to obtain acid vapor and an acid-soluble rare earth concentrate. Mixing of the coal ash with the acid stream can occur in a leaching reactor and heating of the leachate can occur in a roaster. The acid-soluble rare earth concentrate can be fed to a hydrometallurgical process to separate and purify the rare earth elements.

Abstract: The present invention includes formulations and methods to reduce Cr(VI) contamination, in which the formulation comprises (1) a reactive reducing agent comprising at least one reducing chemical capable of reducing Cr(VI) to Cr(III); and (b) one or more solvents. Moreover, the present invention includes formulations to reduce Cr(VI) within the coating, and Cr(VI) reducing kits with at least one color reference tool for evaluating the process and/or completion of the Cr(VI) reduction.

Abstract: A corrosion resistant primer coating comprises one or more corrosion inhibiting additives; and one or more nonaqueous resins, and the method of making and using the primer coating. The corrosion inhibiting additive comprises metal ferrate(IV) compounds, metal ferrate(V) compounds, metal ferrate(VI) compounds, or a mixture thereof (collectively called the ferrate compound). The ferrate compound has a low solubility in water in the range of about 0.001 ppm to about 2000 ppm at a temperature in the range of about 0° C. to 71° C.

Abstract: The present invention includes formulations and methods to reduce Cr(VI) contamination, in which the formulation comprises (1) a reactive reducing agent comprising at least one reducing chemical capable of reducing Cr(VI) to Cr(III); and (b) one or more solvents. Moreover, the present invention includes formulations to reduce Cr(VI) within the coating, and Cr(VI) reducing kits with at least one color reference tool for evaluating the process and/or completion of the Cr(VI) reduction.

Abstract: A corrosion resistant primer coating comprises one or more corrosion inhibiting additives; and one or more nonaqueous resins, and the method of making and using the primer coating. The corrosion inhibiting additive comprises metal ferrate(IV) compounds, metal ferrate(V) compounds, metal ferrate(VI) compounds, or a mixture thereof (collectively called the ferrate compound). The ferrate compound has a low solubility in water in the range of about 0.001 ppm to about 2000 ppm at a temperature in the range of about 0° C. to 71° C.