Abstract

A thermodynamic analysis is carried out for reducing chromium from chromium contacting carbon in gas phase Н₂–Н₂О–СО–СО₂. Considering the normalization condition \({{x}_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}}} + {{x}_{{{{{\text{H}}}_{{\text{2}}}}}}} + {{x}_{{{\text{C}}{{{\text{O}}}_{{\text{2}}}}}}} + {{x}_{{{\text{CO}}}}} = 1\), the oxidizing potential \(\left( {{{p}_{{{{{\text{O}}}_{{\text{2}}}}}}}} \right)\) of the gas phase is determined using two nomograms in coordinates \(\log \left( {\frac{{{{x}_{{{\text{C}}{{{\text{O}}}_{{\text{2}}}}}}}}}{{{{x}_{{{\text{CO}}}}}}}} \right)\)–T and \(\log \left( {\frac{{{{x}_{{{{{\text{H}}}_{2}}{\text{O}}}}}}}{{{{x}_{{{{{\text{H}}}_{2}}}}}}}} \right)\)–T. The potential parameters of chromium reduction from Cr₂O₃ are determined through calculating the ratio of oxide dissociation pressure to the gas phase oxidation potential. In the CO–CO₂–C system, chromium is reduced at a temperature of 1505 K if x_CO > 0.9995. At this temperature, compound Cr₂O₃ is reduced in water-gas having composition \({{x}_{{{{{\text{H}}}_{{\text{2}}}}}}}\) = 0.0186, \({{x}_{{{{{\text{H}}}_{{\text{2}}}}{\text{O}}}}}\) = 0.28 × 10^–4, x_CO = 0.9809, \({{x}_{{{\text{C}}{{{\text{O}}}_{{\text{2}}}}}}}\) = 4.86 × 10^–4; this compound features the oxidation potential equal to the oxide dissociation pressure: \(\log {{\left( {{{p}_{{{{{\text{O}}}_{{\text{2}}}}}}}} \right)}_{{{\text{C}}{{{\text{r}}}_{{\text{2}}}}{{{\text{O}}}_{{\text{3}}}}}}}\) = –17.082. When the hydrogen concentration increases from 0.0186 to 0.9900, the oxidizing potential of water-gas contacting carbon drops by four orders of magnitude: down to \({{\left( {\log {{p}_{{{{{\text{O}}}_{{\text{2}}}}}}}} \right)}_{{{\text{gas}}}}}\) = –21.09. This should result in a significant increase in the recovery rate. Chromium can be reduced in this gaseous atmosphere at a temperature of 1230 K. There is a simple and cheap process to obtain reducing water-gas, for example, by heating water vapor contacting carbon. It is shown that at a temperature of 1500 K, Н₂О and СО₂ traces can be found in water-gas having parameters \({{x}_{{{{{\text{H}}}_{{\text{2}}}}}}}\) = 0.4999, xCO = 0.4996, \(\log \left( {\frac{{{{x}_{{{{{\text{H}}}_{2}}{\text{O}}}}}}}{{{{x}_{{{{{\text{H}}}_{2}}}}}}}} \right)\) = –3.12, \(\log \left( {\frac{{{{x}_{{{\text{C}}{{{\text{O}}}_{{\text{2}}}}}}}}}{{{{x}_{{{\text{CO}}}}}}}} \right)\) = –3.59. The oxidizing potential in this gas is lower than that of chromium oxide with this difference increasing significantly when the temperature grows.

中文翻译：

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从Cr 2 O 3中回收铬的热力学分析。

摘要

热力学分析用于从气相Н铬接触碳还原铬进行₂ -Н ₂ О-СО-СО ₂。考虑归一化条件\（{{x} _ {{{{{{\ text {H}}}} _ {{\ text {2}}}} {\ text {O}}}}} + {{x} _ {{{{{\ text {H}}} _ {{\ text {2}}}}}}} + {{x} _ {{{\ text {C}} {{{\ text {O}} } _ {{\ text {2}}}}}} + {{x} _ {{{\ text {CO}}}}}} = 1 \），氧化电位\（\ left（{{{p } _ {{{{{\ text {O}}} _ {{\ text {2}}}}}}}}}}}}气相的气相色谱法是使用坐标\（\ log \左（{\ frac {{{{x} _ {{{\ text {C}} {{{\ text {O}}} __ {{\ text {2}}}}}}}}} {{{ {x} _ {{{\ text {CO}}}}}}}} \ right）\） – T和\（\ log \ left（{\ frac {{{{x} _ {{{{\ text {H}}} _ {2}} {\ text {O}}}}}}}} {{{{ X} _ {{{{{\文本{H}}} _ {2}}}}}}}} \右）\） - Ť。通过计算氧化物的解离压力与气相氧化电位的比值，可以确定从Cr ₂ O ₃还原铬的电位参数。在CO–CO ₂ –C系统中，如果x _CO > 0.9995 ，则铬在1505 K的温度下会还原。在此温度下，化合物的Cr ₂ ö ₃在具有组合物的水煤气减小\（{{X} _ {{{{{\文本{H}}} _ {{\文本{2}}}}}}} \） = 0.0186，\（{{x} _ {{{{{\ text {H}}}} _ {{\ text {2}}}} {\ text {O}}}}} \） = 0.28× 10 ^–4，x _CO = 0.9809，\（{{x} _ {{{\ text {C}} {{{\ text {O}}} _ {{\ text {2}}}}}}}} \} = 4.86 ×10 ^–4；该化合物的氧化电位等于氧化物的解离压力：\（\ log {{\ left（{{{p} _ {{{{{\ text {O}}} _ {{\ text {2}}} }}}}} \ right）} _ {{{\ text {C}} {{{\ text {r}}} _ {{\ text {2}}}} {{{\ text {O}}} _ {{\ text {3}}}}}} \） = –17.082。当氢气浓度从0.0186增加到0.9900时，与水接触的碳的氧化电位下降了四个数量级：降至\（{{\ left（{\ log {{p} _ {{{{{\ text {O}}} __ {{\ text {2}}}}}}} \ right）} _ {{{\ text {gas}}}}} \）= –21.09。这将导致回收率显着提高。可以在1230 K的温度下在这种气态气氛中还原铬。存在一种简单而廉价的方法，例如通过加热接触碳的水蒸气来获得还原的水煤气。结果表明，在1500 K的温度，Н ₂ О和СО _2个迹线可以在具有参数的水煤气发现\（{{X} _ {{{{{\文本{H}}} _ {{\ text {2}}}}}}} \） = 0.4999，x CO = 0.4996，\（\ log \ left（{\ frac {{{{x} _ {{{{{\ text {H}}}} __ {2}} {\ text {O}}}}}}} {{{{x} _ {{{{{\ text {H}}} _ {2}}}}}}}}} {right} \ ） = –3.12，\（\ log \ left（{\ frac {{{{{x} _ {{{\ text {C}}} {{{\ text {O}}} _ {{\ text {2}} }}}}}}} {{{{x} _ {{{\ text {CO}}}}}}}} \ right）\）= –3.59。该气体中的氧化电势低于氧化铬，随着温度的升高，这种差异显着增加。