Purification of quartz powders by removal of microparticles of refractory materials

Patent metadata

Field	Value
Publication number	US-2021009461-A1
Application number	US-202016925944-A
Country	US
Kind code	A1
Filing date	Jul 10, 2020
Priority date	Jul 12, 2019
Publication date	Jan 14, 2021
Grant date	—

Abstract

Described is a process for the refinement of a quartz powder, comprising the step of separating microparticles of refractory minerals, in particular minerals containing rare earth metal compounds, from the quartz powder by an elutriation step.

First claim

1 . A process for the refinement of a quartz powder, comprising separating microparticles of refractory minerals out of the quartz powder by an elutriation step, wherein the microparticles of refractory minerals comprise minerals containing rare earth metals and/or thorium and/or uranium; and
carrying out the elutriation step in a fluidised bed reactor, in which a controlled upward flow of a liquid elutriation phase is provided, by which the microparticles of refractory minerals are carried upwards in the fluidised bed reactor; whereas the quartz powder remains in the lower region of the fluidised bed reactor.

2 . The process according to claim 1 , wherein the microparticles of refractory minerals carried upwards in the fluidised bed are either discharged out of the fluidised bed reactor or are separated from the liquid elutriation phase.

3 . The process according to claim 2 , wherein the liquid elutriation phase is recycled into the elutriation step and the microparticles of refractory minerals contained therein are separated from the elutriation phase by filtration.

4 . The process according to claim 3 , wherien the microparticles of refractory minerals are separated from the elutriation phase by filtration using a filter with a filter having a pore size of 0.7 μm or less.

5 . The process according to claim 4 , wherein the filter is an acid-resistant filter.

6 . The process according to claim 1 , wherein the separation of the microparticles of refractory minerals from the quartz powder is facilitated by means of ultrasonic agitation before or during elutriation.

7 . The process according to claim 1 , wherein the elutriation step is carried out before or after a calcination and/or hot chlorination step.

8 . The process according to claim 1 , wherein the particle size distribution of the refined quartz powder is homogenised before removal out of the fluidised bed reactor.

9 . The process according to claim 8 , wherein the homogenisation of the refined quartz powder is carried out by agitation, in particular by a flow of a liquid or gas or by ultrasound.

10 . The process according to claim 1 , wherein the quartz powder to be refined has a size from 75 to 1000 μm, whereas the rare earth minerals have a particle size of less than 50 μm.

11 . The process according to claim 1 , wherein the liquid elutriation phase is a leaching an aqueous acid comprising one or more of hydrofluoric, hydrochloric, nitric and sulphuric acids.

12 . A process for the refinement of a quartz powder, comprising separating microparticles of refractory minerals out of the quartz powder by an elutriation step, wherein the quartz powder to be refined has a size from 75 to 1000 μm, whereas the microparticles of refractory minerals have a particle size of less than 50 μm.

13 . Use of an elutriation step for the refinement of a quartz powder by removing rare earth minerals, characterised by the any one of the features of claim 1 .

14 . A refined quartz powder, obtainable according to the refinement process as defined in claim 1 .

15 . A fused quartz glass made from the refined quartz powder according to claim 14 .

Assignees

• Heraeus Quarzglas
• Heraeus Conamic Uk Ltd

Inventors

• Sayce Ian George
• Schindler Michael
• Schildt Fabian
• Visnow Eduard

Classifications

• C03C2201/02

  Pure silica glass, e.g. pure fused quartz · CPC title

• C03C3/06 Primary

  with more than 90% silica by weight, e.g. quartz {(C03C3/045 takes precedence)} · CPC title

• C03C1/022 Primary

  Purification of silica sand or other minerals · CPC title

• C01P2006/80

  Compositional purity · CPC title

• B03B7/00

  Combinations of wet processes or apparatus with other processes or apparatus, e.g. for dressing ores or garbage · CPC title