<?xml version="1.0" encoding="utf-8"?>
<InstanceReport xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>1.0.0.3</Version>
  <hasSegments>false</hasSegments>
  <ReportName>Receivables</ReportName>
  <RoundingOption />
  <Columns>
    <Column>
      <LabelColumn>false</LabelColumn>
      <Id>1</Id>
      <Labels>
        <Label Id="1" Label="12 Months Ended" />
        <Label Id="2" Label="Dec. 31, 2009" />
        <Label Id="4" Label="USD / shares" />
      </Labels>
      <CurrencySymbol>$</CurrencySymbol>
      <hasSegments>false</hasSegments>
      <hasScenarios>false</hasScenarios>
      <Segments />
      <Scenarios />
      <Units>
        <Unit>
          <UnitID>USD</UnitID>
          <UnitType>Standard</UnitType>
          <StandardMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema>
            <MeasureValue>USD</MeasureValue>
            <MeasureNamespace>iso4217</MeasureNamespace>
          </StandardMeasure>
          <Scale>0</Scale>
        </Unit>
        <Unit>
          <UnitID>USDPerShare</UnitID>
          <UnitType>Divide</UnitType>
          <NumeratorMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema>
            <MeasureValue>USD</MeasureValue>
            <MeasureNamespace>iso4217</MeasureNamespace>
          </NumeratorMeasure>
          <DenominatorMeasure>
            <MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema>
            <MeasureValue>shares</MeasureValue>
            <MeasureNamespace>xbrli</MeasureNamespace>
          </DenominatorMeasure>
          <Scale>0</Scale>
        </Unit>
      </Units>
    </Column>
  </Columns>
  <Rows>
    <Row>
      <Id>2</Id>
      <Label>NOTES TO CONSOLIDATED FINANCIAL STATEMENTS</Label>
      <Level>0</Level>
      <ElementName>wlt_NotesToConsolidatedFinancialsAbstract</ElementName>
      <ElementPrefix>wlt</ElementPrefix>
      <IsBaseElement>false</IsBaseElement>
      <BalanceType>na</BalanceType>
      <PeriodType>duration</PeriodType>
      <ElementDataType>string</ElementDataType>
      <ShortDefinition>No definition available.</ShortDefinition>
      <IsReportTitle>false</IsReportTitle>
      <IsSegmentTitle>false</IsSegmentTitle>
      <IsSubReportEnd>false</IsSubReportEnd>
      <IsCalendarTitle>false</IsCalendarTitle>
      <IsTuple>false</IsTuple>
      <IsAbstractGroupTitle>true</IsAbstractGroupTitle>
      <IsBeginningBalance>false</IsBeginningBalance>
      <IsEndingBalance>false</IsEndingBalance>
      <IsEPS>false</IsEPS>
      <Cells>
        <Cell>
          <Id>1</Id>
          <ShowCurrencySymbol>false</ShowCurrencySymbol>
          <IsNumeric>false</IsNumeric>
          <NumericAmount>0</NumericAmount>
          <RoundedNumericAmount>0</RoundedNumericAmount>
          <NonNumbericText />
          <NonNumericTextHeader />
          <FootnoteIndexer />
          <hasSegments>false</hasSegments>
          <hasScenarios>false</hasScenarios>
        </Cell>
      </Cells>
      <ElementDefenition>No definition available.</ElementDefenition>
      <IsTotalLabel>false</IsTotalLabel>
    </Row>
    <Row>
      <Id>3</Id>
      <Label>Receivables</Label>
      <Level>1</Level>
      <ElementName>wlt_ReceivablesTextBlock</ElementName>
      <ElementPrefix>wlt</ElementPrefix>
      <IsBaseElement>false</IsBaseElement>
      <BalanceType>na</BalanceType>
      <PeriodType>duration</PeriodType>
      <ElementDataType>string</ElementDataType>
      <ShortDefinition>Disclosure itemizing the various types of trade accounts and other receivables, and for each the gross carrying value,...</ShortDefinition>
      <IsReportTitle>false</IsReportTitle>
      <IsSegmentTitle>false</IsSegmentTitle>
      <IsSubReportEnd>false</IsSubReportEnd>
      <IsCalendarTitle>false</IsCalendarTitle>
      <IsTuple>false</IsTuple>
      <IsAbstractGroupTitle>false</IsAbstractGroupTitle>
      <IsBeginningBalance>false</IsBeginningBalance>
      <IsEndingBalance>false</IsEndingBalance>
      <IsEPS>false</IsEPS>
      <Cells>
        <Cell>
          <Id>1</Id>
          <ShowCurrencySymbol>false</ShowCurrencySymbol>
          <IsNumeric>false</IsNumeric>
          <NumericAmount>0</NumericAmount>
          <RoundedNumericAmount>0</RoundedNumericAmount>
          <NonNumbericText>&lt;table style="font-size:10pt; font-family:'Times New Roman',times,serif;"&gt;
&lt;tr&gt;
&lt;td&gt;
&lt;p style="FONT-FAMILY: times"&gt;&lt;font size="2"&gt;&lt;b&gt;NOTE 6&amp;#151;Receivables &lt;/b&gt;&lt;/font&gt;&lt;/p&gt;
&lt;p style="FONT-FAMILY: times"&gt;&lt;font size="2"&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;Receivables are summarized as follows (in thousands): &lt;/font&gt;&lt;/p&gt;
&lt;div style="PADDING-RIGHT: 0pt; PADDING-LEFT: 0pt; PADDING-BOTTOM: 0pt; MARGIN-LEFT: 20%; WIDTH: 60%; PADDING-TOP: 0pt; POSITION: relative"&gt;
&lt;p style="FONT-FAMILY: times"&gt;&lt;font size="2"&gt;&lt;!-- COMMAND=ADD_TABLEWIDTH,"100%" --&gt;&lt;/font&gt;&lt;/p&gt;
&lt;!-- User-specified TAGGED TABLE --&gt;
&lt;div align="center"&gt;
&lt;table cellspacing="0" cellpadding="0" width="100%" border="0"&gt;
&lt;tr style="HEIGHT: 0px"&gt;&lt;!-- TABLE COLUMN WIDTHS SET --&gt;
&lt;td style="FONT-FAMILY: times" align="left" width="10"&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" align="left"&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" width="12"&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" align="right" width="7"&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" width="45"&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" width="12"&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" align="right" width="7"&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" width="51"&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" width="12"&gt;&lt;/td&gt;&lt;!-- TABLE COLUMN WIDTHS END --&gt;&lt;/tr&gt;
&lt;tr style="HEIGHT: 0px" valign="bottom"&gt;
&lt;th style="FONT-FAMILY: times" align="left" colspan="2"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;br /&gt;&lt;/th&gt;
&lt;th style="FONT-FAMILY: times"&gt;&lt;font size="1"&gt;&amp;nbsp;&lt;/font&gt;&lt;/th&gt;
&lt;th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="5"&gt;&lt;font size="1"&gt;&lt;b&gt;December&amp;nbsp;31, &lt;/b&gt;&lt;/font&gt;&lt;/th&gt;
&lt;th style="FONT-FAMILY: times"&gt;&lt;font size="1"&gt;&amp;nbsp;&lt;/font&gt;&lt;/th&gt;&lt;/tr&gt;
&lt;tr style="HEIGHT: 0px" valign="bottom"&gt;
&lt;th style="FONT-FAMILY: times" align="left" colspan="2"&gt;&lt;font size="1"&gt;&amp;nbsp;&lt;/font&gt;&lt;br /&gt;&lt;/th&gt;
&lt;th style="FONT-FAMILY: times"&gt;&lt;font size="1"&gt;&amp;nbsp;&lt;/font&gt;&lt;/th&gt;
&lt;th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2"&gt;&lt;font size="1"&gt;&lt;b&gt;2009 &lt;/b&gt;&lt;/font&gt;&lt;/th&gt;
&lt;th style="FONT-FAMILY: times"&gt;&lt;font size="1"&gt;&amp;nbsp;&lt;/font&gt;&lt;/th&gt;
&lt;th style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" align="center" colspan="2"&gt;&lt;font size="1"&gt;&lt;b&gt;2008 &lt;/b&gt;&lt;/font&gt;&lt;/th&gt;
&lt;th style="FONT-FAMILY: times"&gt;&lt;font size="1"&gt;&amp;nbsp;&lt;/font&gt;&lt;/th&gt;&lt;/tr&gt;
&lt;tr style="HEIGHT: 0px" valign="top" bgcolor="#CCEEFF"&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" colspan="2"&gt;
&lt;p style="MARGIN-LEFT: 10pt; TEXT-INDENT: -10pt; FONT-FAMILY: times"&gt;&lt;font size="2"&gt;Trade receivables&lt;/font&gt;&lt;/p&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;$&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;62,379&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;$&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;110,559&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr style="HEIGHT: 0px" valign="top" bgcolor="white"&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" colspan="2"&gt;
&lt;p style="MARGIN-LEFT: 10pt; TEXT-INDENT: -10pt; FONT-FAMILY: times"&gt;&lt;font size="2"&gt;Other receivables&lt;/font&gt;&lt;/p&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;10,748&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;32,707&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr style="HEIGHT: 0px" valign="top" bgcolor="#CCEEFF"&gt;
&lt;td style="FONT-FAMILY: times"&gt;&lt;font size="0"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;
&lt;p style="MARGIN-LEFT: 10pt; TEXT-INDENT: -10pt; FONT-FAMILY: times"&gt;&lt;font size="2"&gt;Less: Allowance for losses&lt;/font&gt;&lt;/p&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;(2,627&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;)&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;(2,843&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;)&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" colspan="2"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="BORDER-BOTTOM: #000000 1pt solid; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&amp;nbsp;&lt;/td&gt;&lt;/tr&gt;
&lt;tr style="HEIGHT: 0px" valign="top" bgcolor="white"&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" colspan="2"&gt;
&lt;p style="MARGIN-LEFT: 10pt; TEXT-INDENT: -10pt; FONT-FAMILY: times"&gt;&lt;font size="2"&gt;Receivables, net&lt;/font&gt;&lt;/p&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;$&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;70,500&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;$&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" align="right"&gt;&lt;font size="2"&gt;140,423&lt;/font&gt;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&lt;font size="2"&gt;&amp;nbsp;&lt;/font&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr style="FONT-SIZE: 1.5pt; HEIGHT: 0px" valign="top"&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom" colspan="2"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="BORDER-BOTTOM: #000000 2.25pt double; FONT-FAMILY: times" valign="bottom" align="right" colspan="2"&gt;&amp;nbsp;&lt;/td&gt;
&lt;td style="FONT-FAMILY: times" valign="bottom"&gt;&amp;nbsp;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;&lt;/div&gt;
&lt;!-- end of user-specified TAGGED TABLE --&gt;&lt;/div&gt;
&lt;p style="FONT-FAMILY: times"&gt;&lt;font size="2"&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;At December&amp;nbsp;31, 2009 and 2008, other receivables includes $6.2&amp;nbsp;million and $29.4&amp;nbsp;million, respectively, relating to a Black Lung Excise Tax refund claim. &lt;/font&gt;&lt;/p&gt;&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;
</NonNumbericText>
          <NonNumericTextHeader>NOTE 6&amp;#151;Receivables
&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;Receivables are summarized as follows (in thousands):


&lt;!-- User-specified TAGGED</NonNumericTextHeader>
          <FootnoteIndexer />
          <hasSegments>false</hasSegments>
          <hasScenarios>false</hasScenarios>
        </Cell>
      </Cells>
      <ElementDefenition>Disclosure itemizing the various types of trade accounts and other receivables, and for each the gross carrying value, allowance, and net carrying value as of the balance sheet date.</ElementDefenition>
      <ElementReferences>No authoritative reference available.</ElementReferences>
      <IsTotalLabel>false</IsTotalLabel>
    </Row>
  </Rows>
  <Footnotes />
  <ComparabilityReport>false</ComparabilityReport>
  <NumberOfCols>1</NumberOfCols>
  <NumberOfRows>2</NumberOfRows>
  <HasScenarios>false</HasScenarios>
  <MonetaryRoundingLevel>UnKnown</MonetaryRoundingLevel>
  <SharesRoundingLevel>UnKnown</SharesRoundingLevel>
  <PerShareRoundingLevel>UnKnown</PerShareRoundingLevel>
  <HasPureData>false</HasPureData>
  <SharesShouldBeRounded>true</SharesShouldBeRounded>
</InstanceReport>
