Abstract: In a method of treating a gas stream (32) containing combustible and/or reactive particles (34) at least a part of the particles (34) contained in the gas stream (32) is separated from the gas stream (32) by means of a separation device (36). The particles (34) separated from the gas stream (32) by means of the separation device (36) are supplied to a collecting vessel (40). The supply of particles (34) to the collecting vessel (40) is interrupted. A flame retardant material (57) is supplied to the collecting vessel (40) so as to form a cover layer of flame retardant material (57) on the particles (34) contained in the collecting vessel (40).

Abstract: An apparatus including a process chamber accommodating a carrier for receiving a raw material powder. An irradiation device of the apparatus is configured to selectively irradiate electromagnetic or particle radiation onto the raw material powder on the carrier in order to produce a work piece by an additive layer construction method, wherein a transmission element allows the transmission of the electromagnetic or particle radiation into the process chamber. The apparatus further includes a gas inlet and a gas outlet for supplying and discharging gas to and from the process chamber which are configured to generate a protective gas stream for protecting the transmission element from being contaminated by impurities present in the process chamber. The gas inlet includes a gas permeable, porous component forming a gas inlet area.

Abstract: An apparatus for producing a three-dimensional work piece comprises a process chamber accommodating a carrier for receiving a raw material powder and an irradiation device for selectively irradiating electromagnetic or particle radiation onto the raw material powder applied onto the carrier in order to produce the work piece from said raw material powder by an additive layer construction method, the irradiation device comprising at least one radiation source and at least one optical unit with a plurality of optical elements. A heat transfer arrangement is configured to transfer heat generated by a heat source to the at least one optical unit of the irradiation device. The apparatus further comprises a control unit configured to control the heat transfer arrangement so as to adjust a temperature of the at least one optical unit of the irradiation device.

Abstract: An apparatus including a process chamber accommodating a carrier for receiving a raw material powder. An irradiation device of the apparatus is configured to selectively irradiate electromagnetic or particle radiation onto the raw material powder on the carrier in order to produce a work piece by an additive layer construction method, wherein a transmission element allows the transmission of the electromagnetic or particle radiation into the process chamber. The apparatus further includes a gas inlet and a gas outlet for supplying and discharging gas to and from the process chamber which are configured to generate a protective gas stream for protecting the transmission element from being contaminated by impurities present in the process chamber. The gas inlet includes a gas permeable, porous component forming a gas inlet area.

Abstract: An apparatus (10) for producing a three-dimensional work piece (12) comprises a process chamber (14) accommodating a carrier (16) for receiving a raw material powder (18) and an irradiation device (20) for selectively irradiating electromagnetic or particle radiation onto the raw material powder (18) applied onto the carrier (16) in order to produce the work piece (12) from said raw material powder (18) by an additive layer construction method, the irradiation device (20) comprising at least one radiation source (22, 24) and at least one optical unit (26, 32) with a plurality of optical elements (28, 34). A heat transfer arrangement (38) is configured to transfer heat generated by a heat source (40) to the at least one optical unit (26, 32) of the irradiation device (20). The apparatus further comprises a control unit (42) configured to control the heat transfer arrangement (38) so as to adjust a temperature of the at least one optical unit (26, 32) of the irradiation device (20).